carpenter: 1000 papers, Hirsch index 26, Hirsch ratio 0.026.
adsauthor "Carpenter, K." abstract sloppy
Title: Improved Techniques for the Fabrication of Frisch
Collar CdZnTe Gamma Ray Spectrometers
Authors: Harrison, Mark J.; Kargar, Alireza; Brooks, Adam C.;
Carpenter, Kenneth H.; McGregor, Douglas S.
Publication: IEEE Transactions on Nuclear Science, vol. 56, issue
3, pp. 1671-1676
Publication Date: 06/2009
Origin: CROSSREF
DOI: 10.1109/TNS.2009.2016660
Bibliographic Code: 2009ITNS...56.1671H
Abstract
Not Available
Title: Transient Processes in the Atmosphere of alpha Tau
Authors: Airapetian, V.; Carpenter, K. G.; Ake, T.
Affiliation: AA(George Mason University/GSFC, Code 667),
AB(NASA/Goddard Space Flight Center, Code 667),
AC(Computer Sciences Corporation/JHU)
Publication: FUTURE DIRECTIONS IN ULTRAVIOLET SPECTROSCOPY: A
Conference Inspired by the Accomplishments of the
Far Ultraviolet Spectroscopic Explorer Mission. AIP
Conference Proceedings, Volume 1135, pp. 215-217
(2009).
Publication Date: 05/2009
Origin: AIP
Keywords: giant stars, interstellar magnetic fields,
ultraviolet radiation effects
Abstract Copyright: (c) 2009: American Institute of Physics
DOI: 10.1063/1.3154052
Bibliographic Code: 2009AIPC.1135..215A
Abstract
Far Ultraviolet Spectrograph Explorer (FUSE) spectra of UV emission
lines observed in alpha Tau at two epochs separated by four months
show dramatic differences in emission line fluxes and line shifts. This
presents the first evidence of dynamic plasma heating in the active
region of this cool giant star. We discuss these observations in terms
of Alfven wave heating in magnetic loops.
Title: The Stellar Imager (SI) project: a deep space
UV/Optical Interferometer (UVOI) to observe the
Universe at 0.1 milli-arcsec angular resolution
Authors: Carpenter, Kenneth G.; Schrijver, Carolus J.;
Karovska, Margarita
Affiliation: AA(Exoplanets and Stellar Astrophysics Laboratory,
NASA-GSFC), AB(Lockheed-Martin Advanced Technology
Center), AC(SAO)
Publication: Astrophysics and Space Science, Volume 320, Issue
1-3, pp. 217-223
Publication Date: 04/2009
Origin: SPRINGER
Keywords: Observatories: space, Interferometry: space, Stars:
surface features, Stars: interiors, Galaxies: AGN,
Planets: Exo-Solar
Abstract Copyright: (c) 2009: Springer Science+Business Media B.V.
DOI: 10.1007/s10509-008-9815-6
Bibliographic Code: 2009Ap&SS.320..217C
Abstract
The Stellar Imager (SI) is a space-based, UV/Optical Interferometer
(UVOI) designed to enable 0.1 milli-arcsecond (mas) spectral imaging of
stellar surfaces and of the Universe in general. It will also probe via
asteroseismology flows and structures in stellar interiors. SI's
science focuses on the role of magnetism in the Universe and will
revolutionize our understanding of the formation of planetary systems,
of the habitability and climatology of distant planets, and of many
magneto-hydrodynamically controlled processes, such as accretion, in the
Universe. The ultra-sharp images of SI will revolutionize our view of
many dynamic astrophysical processes by transforming point sources into
extended sources, and snapshots into evolving views. SI is a
``Flagship and Landmark Discovery Mission'' in the 2005
Heliophysics Roadmap and a potential implementation of the UVOI in the
2006 Science Program for NASA's Astronomy and Physics Division. We
present here the science goals of the SI Mission, a mission architecture
that could meet those goals, and the technology development needed to
enable this mission. Additional information on SI can be found at:
http://hires.gsfc.nasa.gov/si/
.
Title: Hot Ductility of Nb- and Ti-Bearing Microalloyed
Steels and the Influence of Thermal History
Authors: Carpenter, K. R.; Dippenaar, R.; Killmore, C. R.
Affiliation: AA(School of Mechanical, Materials and Mechatronics,
University of Wollongong; BlueScope Steel, Flat
Products), AB(School of Mechanical, Materials and
Mechatronics, University of Wollongong),
AC(BlueScope Steel, Flat Products)
Publication: Metallurgical and Materials Transactions A, Volume
40, Issue 3, pp.573-580
Publication Date: 03/2009
Origin: SPRINGER
Abstract Copyright: (c) 2009: The Minerals, Metals & Materials Society
and ASM International
DOI: 10.1007/s11661-008-9749-1
Bibliographic Code: 2009MMTA...40..573C
Abstract
Not Available
Title: Luciola hypertelescope space observatory: versatile,
upgradable high-resolution imaging, from stars to
deep-field cosmology
Authors: Labeyrie, Antoine; Le Coroller, Hervé
Dejonghe, Julien; Lardière, Olivier; Aime, Claude;
Dohlen, Kjetil; Mourard, Denis; Lyon, Richard;
Carpenter, Kenneth G.
Affiliation: AA(Collège de France; , Observatoire de la Côte
d'Azur), AB(Observatoire de Haute Provence),
AC(Collège de France), AD(Adaptive Optics Lab,
University of Victoria), AE(Université de
Nice-Sophia Antipolis), AF(Observatoire Astronomique
Marseille Provence), AG(Observatoire de la Côte
d'Azur), AH(NASA Goddard Space Flight Center),
AI(NASA Goddard Space Flight Center)
Publication: Experimental Astronomy, Volume 23, Issue 1,
pp.463-490
Publication Date: 03/2009
Origin: SPRINGER
Keywords: Space interferometer, Hypertelescope,
High-resolution, Exo-planet
Abstract Copyright: (c) 2009: Springer Science+Business Media B.V.
DOI: 10.1007/s10686-008-9123-8
Bibliographic Code: 2009ExA....23..463L
Abstract
Luciola is a large (1 km) ``multi-aperture densified-pupil imaging
interferometer'', or ``hypertelescope'' employing many
small apertures, rather than a few large ones, for obtaining direct
snapshot images with a high information content. A diluted collector
mirror, deployed in space as a flotilla of small mirrors, focuses a sky
image which is exploited by several beam-combiner spaceships. Each
contains a ``pupil densifier'' micro-lens array to avoid the
diffractive spread and image attenuation caused by the small
sub-apertures. The elucidation of hypertelescope imaging properties
during the last decade has shown that many small apertures tend to be
far more efficient, regarding the science yield, than a few large ones
providing a comparable collecting area. For similar underlying physical
reasons, radio-astronomy has also evolved in the direction of
many-antenna systems such as the proposed Low Frequency Array having
``hundreds of thousands of individual receivers''. With its
high limiting magnitude, reaching the m v = 30 limit of HST
when 100 collectors of 25 cm will match its collecting area,
high-resolution direct imaging in multiple channels, broad spectral
coverage from the 1,200 Å ultra-violet to the 20 mum infra-red,
apodization, coronagraphic and spectroscopic capabilities, the proposed
hypertelescope observatory addresses very broad and innovative science
covering different areas of ESA's Cosmic Vision program. In the
initial phase, a focal spacecraft covering the UV to near IR spectral
range of EMCCD photon-counting cameras (currently 200 to 1,000 nm), will
image details on the surface of many stars, as well as their
environment, including multiple stars and clusters. Spectra will be
obtained for each resel. It will also image neutron star, black-hole and
micro-quasar candidates, as well as active galactic nuclei, quasars,
gravitational lenses, and other Cosmic Vision targets observable with
the initial modest crowding limit. With subsequent upgrade missions, the
spectral coverage can be extended from 120 nm to 20 mum, using four
detectors carried by two to four focal spacecraft. The number of
collector mirrors in the flotilla can also be increased from 12 to 100
and possibly 1,000. The imaging and spectroscopy of habitable exoplanets
in the mid infra-red then becomes feasible once the collecting area
reaches 6 m2, using a specialized mid infra-red focal
spacecraft. Calculations (Boccaletti et al., Icarus 145, 628--636,
2000) have
shown that hypertelescope coronagraphy has unequalled sensitivity for
detecting, at mid infra-red wavelengths, faint exoplanets within the
exo-zodiacal glare. Later upgrades will enable the more difficult
imaging and spectroscopy of these faint objects at visible wavelengths,
using refined techniques of adaptive coronagraphy (Labeyrie and Le
Coroller 2004).
Together, the infra-red and visible spectral data carry rich information
on the possible presence of life. The close environment of the central
black-hole in the Milky Way will be imageable with unprecedented detail
in the near infra-red. Cosmological imaging of remote galaxies at the
limit of the known universe is also expected, from the ultra-violet to
the near infra-red, following the first upgrade, and with greatly
increasing sensitivity through successive upgrades. These areas will
indeed greatly benefit from the upgrades, in terms of dynamic range,
limiting complexity of the objects to be imaged, size of the elementary
``Direct Imaging Field'', and limiting magnitude, approaching
that of an 8-m space telescope when 1,000 apertures of 25 cm are
installed. Similar gains will occur for addressing fundamental problems
in physics and cosmology, particularly when observing neutron stars and
black holes, single or binary, including the giant black holes, with
accretion disks and jets, in active galactic nuclei beyond the Milky
Way. Gravitational lensing and micro-lensing patterns, including
time-variable patterns and perhaps millisecond lensing flashes which may
be beamed by diffraction from sub-stellar masses at sub-parsec distances
(Labeyrie, Astron Astrophys 284, 689, 1994), will also be observable
initially in the favourable cases, and upgrades will greatly improve the
number of observable objects. The observability of gravitational waves
emitted by binary lensing masses, in the form of modulated lensing
patterns, is a debated issue (Ragazzoni et al., MNRAS 345,
100--110, 2003) but will also become
addressable observationally. The technology readiness of Luciola
approaches levels where low-orbit testing and stepwise implementation
will become feasible in the 2015--2025 time frame. For the
following decades beyond 2020, once accurate formation flying techniques
will be mastered, much larger hypertelescopes such as the proposed 100
km Exo-Earth Imager and the 100,000 km Neutron Star Imager should also
become feasible. Luciola is therefore also seen as a precursor toward
such very powerful instruments.
Title: Heavy Elements and Cool Stars
Authors: Wahlgren, Glenn M.; Carpenter, Kenneth G.;
Norris, Ryan P.
Affiliation: AA(NASA-GSFC, Code 667, Greenbelt, MD, USA 20071;
Catholic Univ of America, Dept of Physics, 620
Michigan Ave NE, Washington DC, USA 20064),
AB(NASA-GSFC, Code 667, Greenbelt, MD, USA 20071),
AC(NASA-GSFC, Code 667, Greenbelt, MD, USA 20071;
Catholic Univ of America, Dept of Physics, 620
Michigan Ave NE, Washington DC, USA 20064)
Publication: COOL STARS, STELLAR SYSTEMS AND THE SUN: Proceedings
of the 15th Cambridge Workshop on Cool Stars,
Stellar Systems and the Sun. AIP Conference
Proceedings, Volume 1094, pp. 892-895 (2009).
Publication Date: 02/2009
Origin: AIP
Keywords: giant stars, nucleosynthesis, celestial mechanics
Abstract Copyright: (c) 2009: American Institute of Physics
DOI: 10.1063/1.3099261
Bibliographic Code: 2009AIPC.1094..892W
Abstract
We report on progress in the analysis of high-resolution near-IR spectra
of alpha Orionis (M2 Iab) and other cool, luminous stars. Using
synthetic spectrum techniques, we search for atomic absorption lines in
the stellar spectra and evaluate the available line parameter data for
use in our abundance analyses. Our study concentrates on the post
iron-group elements copper through zirconium as a means of investigating
the slow neutron-capture process of nucleosynthesis in massive stars and
the mechanisms that transport recently processed material up into the
photospheric region. We discuss problems with the atomic data and model
atmospheres that need to be addressed before theoretically derived
elemental abundances from pre-supernova nucleosynthesis calculations can
be tested by comparison with abundances determined from observations of
cool, massive stars.
Title: UV, IR, and mm Studies of CO Surrounding the Red
Supergiant alpha Orionis (M2 Iab)
Authors: Harper, Graham M.; Carpenter, Kenneth G.; Ryde, Nils;
Smith, Nathan; Brown, Joanna; Brown, Alexander;
Hinkle, Kenneth H.
Affiliation: AA(CASA, University of Colorado, Boulder, Colorado,
USA), AB(NASA-Goddard Space Flight Center, USA),
AC(Lund Observatory, Sweden), AD(University of
California, Berkley, USA), AE(Max-Planck-Institut
für Extraterrestrische Physik, Germany), AF(CASA,
University of Colorado, Boulder, Colorado, USA),
AG(National Optical Astronomy Observatory, Tucson,
Arizona, USA)
Publication: COOL STARS, STELLAR SYSTEMS AND THE SUN: Proceedings
of the 15th Cambridge Workshop on Cool Stars,
Stellar Systems and the Sun. AIP Conference
Proceedings, Volume 1094, pp. 868-871 (2009).
Publication Date: 02/2009
Origin: AIP
Keywords: giant stars, infrared astronomy, radiative transfer
Abstract Copyright: (c) 2009: American Institute of Physics
DOI: 10.1063/1.3099254
Bibliographic Code: 2009AIPC.1094..868H
Abstract
Carbon monoxide has been detected in Betelgeuse's ultraviolet
(electronic), infrared (vibrational), and mm-radio (rotational) spectra,
but its spatial distribution has remained elusive. We have obtained new
mm-radio interferometry (CARMA), infrared spatially-resolved spectra
(Phoenix/Gemini-South), and we have performed non-LTE simulations to
help establish the spatial location of the S1 (V = 10 km/s) and S2 (V =
17 km/s) CO shells. The strong CO Fourth-Positive ultraviolet scattering
signature is apparent in the HST GHRS G140L spectrum and the S1 and S2
shells account for much of the UV opacity. Phoenix spectra reveal that
the low velocity S1 shell is present at 1.5 arcsec West of the star and
extends out to ~4 arcsec, and its mm-radio emission appears to originate
within an 6 arcsec radius. The interpretation of the S2 shell is less
clear. The Phoenix spectra tentatively suggest that the S2 shell extends
to ~7 arcsec. The CARMA channel maps show an additional strong narrow
emission component 5 arcsec from the star, but the spectra do not show
all the expected S1 and S2 signatures. Future CARMA observations should
help to disentangle the signature of the S1 and S2 shells.
Title: The Atmospheric Dynamics of alpha Tau (K5 III)-Clues to
Understanding the Magnetic Dynamo in Late-Type Giant
Stars
Authors: Carpenter, Kenneth G.; Airapetian, Vladimir
Affiliation: AA(Exoplanets and Stellar Astrophysics Laboratory,
Code 667, NASA-Goddard Space Flight Center,
Greenbelt, MD 20771), AB(Catholic University of
America at NASA-GSFC, Greenbelt, MD 20771)
Publication: COOL STARS, STELLAR SYSTEMS AND THE SUN: Proceedings
of the 15th Cambridge Workshop on Cool Stars,
Stellar Systems and the Sun. AIP Conference
Proceedings, Volume 1094, pp. 712-715 (2009).
Publication Date: 02/2009
Origin: AIP
Keywords: giant stars, magnetohydrodynamic waves, stellar
atmospheres
Abstract Copyright: (c) 2009: American Institute of Physics
DOI: 10.1063/1.3099213
Bibliographic Code: 2009AIPC.1094..712C
Abstract
Using HST/GHRS, HST/STIS and FUSE archival data for alpha Tau and the
CHIANTI spectroscopic code, we have derived line shifts, volumetric
emission measures, and plasma density estimates, and calculated filling
factors for a number of UV lines forming between 10,000 K and 300,000 K
in the outer atmosphere of this red giant star. The data suggest the
presence of low-temperature extended regions and high-temperature
compact regions, associated with magnetically open and closed structures
in the stellar atmosphere, respectively. The signatures of UV lines from
alpha Tau can be consistently understood via a model of
upward-traveling Alfvén waves in a gravitationally stratified
atmosphere. These waves cause nonthermal broadening in UV lines due to
unresolved wave motions and downward plasma motions in compact magnetic
loops heated by resonant Alfvén wave heating.
Title: Stellar Imager (SI) - Observing the Universe in High
Definition
Authors: Carpenter, Kenneth G.; Karovska, M.;
Schrijver, C. J.; SI Development Team
Affiliation: AA(NASA's GSFC), AB(Harvard Smithsonian, CfA),
AC(Lockheed Martin Advanced Technology Center), AD()
Publication: American Astronomical Society, AAS Meeting \#213,
\#451.13; Bulletin of the American Astronomical
Society, Vol. 41, p.346; Bulletin of the American
Astronomical Society, Vol. 41, p.346
Publication Date: 01/2009
Origin: AAS
Abstract Copyright: (c) 2009: American Astronomical Society
Bibliographic Code: 2009AAS...21345113C
Abstract
Stellar Imager (http://hires.gsfc.nasa.gov/si/) is a space-based,
UV/Optical Interferometer (UVOI) with over 200x HST's resolution. It
will enable 0.1 milli-arcsec spectral imaging of stellar surfaces and
the Universe in general and open an enormous new "discovery space" for
Astrophysics with its combination of high angular resolution, dynamic
imaging, and spectral energy resolution. SI's goal is to study the role
of magnetism in the Universe and revolutionize our understanding of: 1)
Solar/Stellar Magnetic Activity and their impact on Space Weather,
Planetary Climates, and Life, 2) Magnetic and Accretion Processes and
their roles in the Origin and Evolution of Structure and in the
Transport of Matter throughout the Universe, 3) the close-in structure
of Active Galactic Nuclei, and 4) Exo-Solar Planet Transits and Disks.
The SI mission is targeted for the mid 2020's - thus significant
technology development in the upcoming decade is critical to enabling it
and future space-based sparse aperture telescope and distributed
spacecraft missions. The key technology needs include: 1) precision
formation flying of many spacecraft, 2) precision metrology over
km-scales, 3) closed-loop control of many-element, sparse optical
arrays, 4) staged-control systems with very high dynamic ranges (nm to
km-scale). It is critical that the importance of timely development of
these capabilities is called out in the upcoming Astrophysics and
Heliophysics Decadal Surveys, to enable the flight of such missions in
the following decade. SI is a "Landmark/Discovery Mission" in the 2005
Heliophysics Roadmap and a candidate UVOI in the 2006 Astrophysics
Strategic Plan. It is a NASA Vision Mission ("NASA Space Science Vision
Missions" (2008), ed. M. Allen) and has also been recommended for
further study in the 2008 NRC interim report on missions potentially
enabled or enhanced by an Ares V launch, although an
incrementally-deployed version could be launched using smaller rockets.
Title: Technology Development for Future Sparse Aperture
Telescopes and Interferometers in Space
Authors: Carpenter, Kenneth G.; Gendreau, Keith;
Leitner, Jesse; Lyon, Richard; Stoneking, Eric;
Stahl, H. Philip; Parrish, Joe;
Schrijver, Carolus J.; Woodruff, Robert;
Lillie, Chuck; Lo, Amy; Mozurkewich, David;
Labeyrie, Antoine; Miller, David; Mighell, Ken;
Karovska, Margarita; Phillips, James;
Allen, Ronald J.; Cash, Webster
Publication: Astro2010: The Astronomy and Astrophysics Decadal
Survey, Technology Development Papers, no. 47
Publication Date: 00/2009
Origin: ADS
Bibliographic Code: 2009astro2010T..47C
Abstract
Not Available
Title: Dynamos and magnetic fields of the Sun and other
cool stars, and their role in the formation and
evolution of stars and in the habitability of
planets
Authors: Schrijver, Karel; Carpenter, Ken;
Karovska, Margarita; Ayres, Tom; Basri, Gibor;
Brown, Benjamin; Christensen-Dalsgaard, Joergen;
Dupree, Andrea; Guinan, Ed; Jardine, Moira;
Miesch, Mark; Pevtsov, Alexei; Rempel, Matthias;
Scherrer, Phil; Solanki, Sami; Strassmeier, Klaus;
Walter, Fred
Publication: Astro2010: The Astronomy and Astrophysics Decadal
Survey, Science White Papers, no. 262
Publication Date: 00/2009
Origin: ADS
Bibliographic Code: 2009astro2010S.262S
Abstract
Not Available
Title: Active Galactic Nuclei and their role in Galaxy
Formation and Evolution
Authors: Kraemer, Steve; Windhorst, Rogier;
Carpenter, Kenneth G.; Crenshaw, Mike; Elvis, Martin;
Karovska, Margarita
Publication: Astro2010: The Astronomy and Astrophysics Decadal
Survey, Science White Papers, no. 162
Publication Date: 00/2009
Origin: ADS
Bibliographic Code: 2009astro2010S.162K
Abstract
There are several key open questions as to the nature and origin of AGN
including: 1) what initiates the active phase, 2) the duration of the
active phase, and 3) the effect of the AGN on the host galaxy. Critical
new insights to these can be achieved by probing the central regions of
AGN with sub-mas angular resolution at UV/optical wavelengths. In
particular, such observations would enable us to constrain the
energetics of the AGN "feedback" mechanism, which is critical for
understanding the role of AGN in galaxy formation and evolution. These
observations can only be obtained by long-baseline interferometers or
sparse aperture telescopes in space, since the aperture diameters
required are in excess of 500 m - a regime in which monolithic or
segmented designs are not and will not be feasible and because these
observations require the detection of faint emission near the bright
unresolved continuum source, which is impossible from the ground, even
with adaptive optics. Two mission concepts which could provide these
invaluable observations are NASA's Stellar Imager (SI; Carpenter et al.
2008 & http://hires.gsfc.nasa.gov/si/) interferometer and ESA's
Luciola (Labeyrie 2008) sparse aperture hypertelescope.
Title: Mass Transport Processes and their Roles in the
Formation, Structure, and Evolution of Stars and
Stellar Systems
Authors: Carpenter, Kenneth G.; Karvovska, Margarita;
Schrijver, Carolus J.; Grady, Carol A.;
Allen, Ronald J.; Brown, Alexander;
Cranmer, Steven R.; Dupree, Andrea K.;
Evans, Nancy R.; Guinan, Edward F.; Harper, Graham;
Labeyrie, Antoine; Linsky, Jeffrey;
Peters, Geraldine J.; Roberge, Aki; Saar, Steven H.;
Sonneborn, George; Walter, Frederick M.
Publication: Astro2010: The Astronomy and Astrophysics Decadal
Survey, Science White Papers, no. 40
Publication Date: 00/2009
Origin: ADS
Bibliographic Code: 2009astro2010S..40C
Abstract
We summarize some of the compelling new scientific opportunities for
understanding stars and stellar systems that can be enabled by sub-mas
angular resolution, UV/Optical spectral imaging observations, which can
reveal the details of the many dynamic processes (e.g., variable
magnetic fields, accretion, convection, shocks, pulsations, winds, and
jets) that affect their formation, structure, and evolution. These
observations can only be provided by long-baseline interferometers or
sparse aperture telescopes in space, since the aperture diameters
required are in excess of 500 m - a regime in which monolithic or
segmented designs are not and will not be feasible - and since they
require observations at wavelengths (UV) not accessible from the ground.
Two mission concepts which could provide these invaluable observations
are NASA's Stellar Imager (SI; http://hires.gsfc.nasa.gov/si/)
interferometer and ESA's Luciola sparse aperture hypertelescope, which
each could resolve hundreds of stars and stellar systems. These
observatories will also open an immense new discovery space for
astrophysical research in general and, in particular, for Active
Galactic Nuclei (Kraemer et al. Decadal Survey Science Whitepaper). The
technology developments needed for these missions are challenging, but
eminently feasible (Carpenter et al. Decadal Survey Technology
Whitepaper) with a reasonable investment over the next decade to enable
flight in the 2025+ timeframe. That investment would enable tremendous
gains in our understanding of the individual stars and stellar systems
that are the building blocks of our Universe and which serve as the
hosts for life throughout the Cosmos.
Title: Commission 29: Stellar Spectra
Authors: Parthasarathy, Mudumba; Piskunov, Nikolai E.;
Sneden, Christopher; Carpenter, Kenneth G.;
Castelli, Fiorella; Cunha, Katia;
Eenens, Phillippe R. J.; Huben{\'{y}}, Ivan; Rossi, Silvia;
Takada-Hidai, Masahide; Wahlgren, Glenn M.;
Weiss, Werner W.
Publication: Transactions IAU, Volume 4, Issue 27A, Reports on
Astronomy 2006-2009. Edited by Karel van der Hucht.
Cambridge: Cambridge University Press, 2008, p.
209-210
Publication Date: 12/2008
Origin: CUP
Abstract Copyright: (c) 2008: Copyright © International Astronomical
Union 2009
DOI: 10.1017/S1743921308025532
Bibliographic Code: 2008IAUTA..27..209P
Abstract
The members of IAU Commission 29 Stellar Spectra are actively engaged in
the quantitative analysis of spectra of various types of stars. With
large and medium size telescopes equipped with high resolution
spectrographs LTE and Non-LTE analysis of spectra of all types stars are
being carried out. Spectra of stars in our Galaxy, in globular and open
clusters, stars in LMC and SMC and in nearby galaxies are being studied.
Accurate chemical composition analysis of various types of stars has
been carried out during the past three years. Now the analysis of
stellar spectra covers the wavelength range from X-ray region to IR and
sub-millimeter range. Recently stellar spectra are being analysed using
time-dependent, 3D, hydrodynamical model atmospheres to derive accurate
stellar abundances.
Title: Stellar Imager: wavefront control
Authors: Lyon, Richard G.; Carpenter, Kenneth G.;
Petrone, Peter; Dogoda, Peter; Reed, Daniel;
Mozurkewich, David
Affiliation: AA(NASA Goddard Space Flight Ctr. (United States)),
AB(NASA Goddard Space Flight Ctr. (United States)),
AC(Sigma Space (United States)), AD(Sigma Space
(United States)), AE(Sigma Space (United States)),
AF(Seabrook Engineering (United States))
Publication: Space Telescopes and Instrumentation 2008:
Ultraviolet to Gamma Ray. Edited by Turner, Martin
J. L.; Flanagan, Kathryn A. Proceedings of the
SPIE, Volume 7011, pp. 701131-701131-12 (2008).
Publication Date: 08/2008
Origin: SPIE
Abstract Copyright: (c) 2008: SPIE--The International Society for
Optical Engineering. Downloading of the abstract is
permitted for personal use only.
DOI: 10.1117/12.789758
Bibliographic Code: 2008SPIE.7011E..89L
Abstract
Stellar Imager (SI) is a proposed NASA space-based UV imaging
interferometer to resolve the stellar disks of nearby stars. SI would
consist of 20 - 30 separate spacecraft flying in formation at the
Earth-Sun L2 libration point. Onboard wavefront sensing and control is
required to maintain alignment during science observations and after
array reconfigurations. The Fizeau Interferometry Testbed (FIT),
developed at the NASA/Goddard Space Flight Center, is being used to
study wavefront sensing and control methodologies for Stellar Imager and
other large, sparse aperture telescope systems. FIT initially consists
of 7 articulated spherical mirrors in a Golay pattern, and is currently
undergoing expansion to 18 elements. FIT currently uses in-focus
whitelight sparse aperture PSFs and a direct solve broadband phase
retrieval algorithm to sense and control its wavefront. Ultimately it
will use extended scene wavelength, with a sequential diversity
algorithm that modulates a subset of aperture pistons to jointly
estimate the wavefront and the reconstructed image from extended scenes.
The recovered wavefront is decomposed into the eigenmodes of the control
matrix and actuators are moved to minimize the wavefront piston, tip and
tilt in closed-loop. We discuss the testbed, wavefront control
methodology and ongoing work to increase its bandwidth from 1 per 11
seconds to a few 10's of Hertz and show ongoing results.
Title: One-Third of Reef-Building Corals Face Elevated
Extinction Risk from Climate Change and Local
Impacts
Authors: Carpenter, Kent E.; Abrar, Muhammad; Aeby, Greta;
Aronson, Richard B.; Banks, Stuart; Br{\"{u}}ckner, Andrew;
Chiriboga, Angel; Cortés, Jorge; Delbeek, J. Charles;
DeVantier, Lyndon; Edgar, Graham J.;
Edwards, Alasdair J.; Fenner, Douglas;
Guzmán, Héctor M.; Hoeksema, Bert W.;
Hodgson, Gregor; Johan, Ofri; Licuanan, Wilfredo Y.;
Livingstone, Suzanne R.; Lovell, Edward R.;
Moore, Jennifer A.; Obura, David O.;
Ochavillo, Domingo; Polidoro, Beth A.;
Precht, William F.; Quibilan, Miledel C.;
Reboton, Clarissa; Richards, Zoe T.; Rogers, Alex D.;
Sanciangco, Jonnell; Sheppard, Anne;
Sheppard, Charles; Smith, Jennifer; Stuart, Simon;
Turak, Emre; Veron, John E. N.; Wallace, Carden;
Weil, Ernesto; Wood, Elizabeth
Affiliation: AA(IUCN (International Union for Conservation of
Nature) Species Programme Species Survival
Commission (SSC) and Conservation International (CI)
Global Marine Species Assessment, Biological
Sciences, Old Dominion University, Norfolk, VA
23529, USA.), AB(Research Center for Oceanography,
Indonesian Institute of Sciences, Jakarta,
Indonesia.), AC(Hawaii Institute of Marine Biology,
Kaneohe, HI 96744, USA.), AD(Dauphin Island Sea Lab,
Dauphin Island, AL 36528, USA.), AE(Charles Darwin
Research Station, Puerto-Ayora,
Santa-Cruz-Galápagos, Ecuador.), AF(National Oceanic
and Atmospheric Administration (NOAA) Fisheries and
NOAA Coral Reef Conservation Program, Silver Spring,
MD 20910, USA.), AG(Brown University, Providence, RI
02912, USA.), AH(Centro de Investigacion en Ciencias
del Mar y Limnologia (CIMAR), University of Costa
Rica, San José, Costa Rica.), AI(Waikiki Aquarium,
University of Hawaii at Manoa, Honolulu, HI 96822,
USA.), AJ(Coral Reef Research, Townsville,
Queensland 4811, Australia.), AK(Center for Applied
Biodiversity Science (CABS), CI, Arlington, VA
22202, USA.; Tasmanian Aquaculture and Fisheries
Institute, University of Tasmania, Hobart, Tasmania
7011, Australia.), AL(School of Biology, Newcastle
University, Newcastle upon Tyne NE1 7RU, UK.),
AM(Department of Marine and Wildlife Resources, Pago
Pago, American Samoa, USA.), AN(Smithsonian Tropical
Research Institute, Balboa 0843-03092, Panama.),
AO(National Museum of Natural History Naturalis,
Leiden 2333, Netherlands.), AP(Reef Check
Foundation, Pacific Palisades, CA 90272, USA.),
AQ(Research Center for Aquaculture, Minggu, Jakarta
Selatan, Indonesia.), AR(Biology Department and
Shields Marine Station, De La Salle University,
Manila, Philippines.), AS(IUCN (International Union
for Conservation of Nature) Species Programme
Species Survival Commission (SSC) and Conservation
International (CI) Global Marine Species Assessment,
Biological Sciences, Old Dominion University,
Norfolk, VA 23529, USA.), AT(School of Marine
Studies, University of the South Pacific, Suva,
Fiji.), AU(NOAA Fisheries Service, Protected
Resources Division, St. Petersburg, FL 33701, USA.),
AV(Coastal Oceans Research and Development in the
Indian Ocean (CORDIO) East Africa, Mombasa, Kenya.),
AW(Reef Check Philippines, Manila, Philippines.),
AX(IUCN (International Union for Conservation of
Nature) Species Programme Species Survival
Commission (SSC) and Conservation International (CI)
Global Marine Species Assessment, Biological
Sciences, Old Dominion University, Norfolk, VA
23529, USA.), AY(NOAA, Florida Keys National Marine
Sanctuary, Damage Assessment and Restoration
Program, Key Largo, FL 33040, USA.),
AZ(Sulu-Sulawesi Seascape Program, CI Philippines,
Quezon City, Philippines.), BA(Silliman University,
Institute of Environmental and Marine Sciences,
Bantayan, Dumaguete City, Philippines.),
BB(Australian Research Council Centre of Excellence
for Coral Reef Studies, James Cook University,
Townsville, Queensland 4811, Australia.),
BC(Zoological Society of London, Institute of
Zoology, London NW1 4RY, UK.), BD(IUCN
(International Union for Conservation of Nature)
Species Programme Species Survival Commission (SSC)
and Conservation International (CI) Global Marine
Species Assessment, Biological Sciences, Old
Dominion University, Norfolk, VA 23529, USA.),
BE(Department of Biological Science, University of
Warwick, Coventry CV4 7AL, UK.), BF(Department of
Biological Science, University of Warwick, Coventry
CV4 7AL, UK.), BG(IUCN (International Union for
Conservation of Nature) Species Programme Species
Survival Commission (SSC) and Conservation
International (CI) Global Marine Species Assessment,
Biological Sciences, Old Dominion University,
Norfolk, VA 23529, USA.), BH(IUCN SSC and CI CABS
Biodiversity Assessment Unit, Conservation
International, Arlington, VA 23529, USA.), BI(Coral
Reef Research, Townsville, Queensland 4811,
Australia.), BJ(Coral Reef Research, Townsville,
Queensland 4811, Australia.), BK(Museum of Tropical
Queensland, Townsville, Queensland 4810,
Australia.), BL(Department of Marine Sciences,
University of Puerto Rico, Lajas, PR, USA.),
BM(Marine Conservation Society, Ross-on-Wye,
Herefordshire HR9 5NB, UK.)
Publication: Science, Volume 321, Issue 5888, pp. 560- (2008).
Publication Date: 07/2008
Category: ECOLOGY
Origin: SCIENCE
Abstract Copyright: (c) 2008: Science
DOI: 10.1126/science.1159196
Bibliographic Code: 2008Sci...321..560C
Abstract
The conservation status of 845 zooxanthellate reef-building coral
species was assessed by using International Union for Conservation of
Nature Red List Criteria. Of the 704 species that could be assigned
conservation status, 32.8% are in categories with elevated risk of
extinction. Declines in abundance are associated with bleaching and
diseases driven by elevated sea surface temperatures, with extinction
risk further exacerbated by local-scale anthropogenic disturbances. The
proportion of corals threatened with extinction has increased
dramatically in recent decades and exceeds that of most terrestrial
groups. The Caribbean has the largest proportion of corals in high
extinction risk categories, whereas the Coral Triangle (western Pacific)
has the highest proportion of species in all categories of elevated
extinction risk. Our results emphasize the widespread plight of coral
reefs and the urgent need to enact conservation measures.
Title: Atmospheric Dynamics in alpha Tau
Authors: Airapetian, Vladimir; Carpenter, K. G.
Affiliation: AA(The Catholic University of America/NASA/GSFC),
AB(NASA/GSFC)
Publication: American Astronomical Society, AAS Meeting \#211,
\#162.15
Publication Date: 03/2008
Origin: AAS
Abstract Copyright: (c) 2008: American Astronomical Society
Bibliographic Code: 2008AAS...21116215A
Abstract
HST/GHRS, HST/STIS and FUSE observations of evolved late-type stars
demonstrated the presence of non-thermally broadened UV emission lines
forming at temperatures of 10,000 to 300,000K in almost all of the
stars. In this study we analyze CI 1993.62A, CII] 2323.5A, SiIII
2350.17A, SiIV 1393A, CIII 977A, OIV 1401.35A and OVI 1032A emission
lines from Tau. Our analysis of these UV lines reveal redshifts T
(except for OVI 1032A), while non-thermal velocities T. Derived
emission measures indicate filling factors <0.1%. These findings
force us to reconsider the definition of chromospheric and transition
regions in these stars as patchy regions or atmospheric hot spots.
According to Freytag et al. (2002), convective cells with sizes of
0.01Rstar generate shock waves that dissipate at lower
atmospheric layers. Large-scale convective motions produce large-scale
magnetic structures in contrast to arcades of thin solar-like loops
powered by small-scale granular motions. We discuss the model of
non-linear Alfven waves amplified by resonant interaction with sound
waves and propagating upward along one (or a few) constant pressure
large-scale loop(s). As Alfven waves propagate upward in a
gravitationally stratified atmosphere, their wave amplitudes increase
causing non-thermal broadening in UV lines due to unresolved wave
motions. We discuss a model that predicts downward plasma motions in
extended loops driven by asymmetric Alfven wave heating. We use a
state-of-the-art 2.5 MHD code to show that the energy flux density of
Alfven waves (with P a few days), which are needed to explain the
radiative cooling and non-thermal broadening in the UV lines, is
consistent with the requirement to drive massive ( 10
MSun/yr) and slow ( 30 km/s) stellar winds from magnetically
open structures with the assumption of a magnetic field at the wind base
1 G.
This research is supported by the NASA Research grant to CUA from GSFC
No. NASA-NNG06GJ29G
Title: Towards a Small Prototype Planet Finding
Interferometer: The next step in planet finding and
characterization in the infrared
Authors: Danchi, W. C.; Deming, D.; Carpenter, K. G.;
Barry, R. K.; Hinz, P.; Johnston, K. J.; Lawson, P.;
Lay, O.; Monnier, J. D.; Richardson, L. J.;
Rinehart, S.; Traub, W.
Publication: eprint arXiv:0801.4752
Publication Date: 01/2008
Origin: ARXIV
Keywords: Astrophysics
Comment: 8 pages, 4 figures, white paper for Exoplanet Task
Force, March 2007
Bibliographic Code: 2008arXiv0801.4752D
Abstract
During the last few years, considerable effort has been directed towards
large-scale (>> $1 Billion US) missions to detect and characterize
earth-like planets around nearby stars, such as the Terrestrial Planet
Finder Interferometer (TPF-I) and Darwin missions. However,
technological and budgetary issues as well as shifting science
priorities will likely prevent these missions from entering Phase A
until the next decade. The secondary eclipse technique using the Spitzer
Space Telescope has been used to directly measure the temperature and
emission spectrum of extrasolar planets. However, only a small fraction
of known extrasolar planets are in transiting orbits. Thus, a simplified
nulling interferometer, which produces an artificial eclipse or
occultation, and operates in the near- to mid-infrared (e.g. ~ 3 to 8 or
10 microns), can characterize the atmospheres of this much larger sample
of the known but non-transiting exoplanets. Many other scientific
problems can be addressed with a system like this, including imaging
debris disks, active galactic nuclei, and low mass companions around
nearby stars. We discuss the rationale for a probe-scale mission in the
$600-800 Million range, which we name here as the Small Prototype Planet
Finding Interferometer (SPPFI).
Title: Beam combination for Stellar Imager and its
application to full-aperture imaging
Authors: Mozurkewich, D.; Carpenter, K. G.; Lyon, R. G.
Affiliation: AA(Seabrook Engineering (USA)), AB(NASA Goddard
Space Flight Ctr. (USA)), AC(NASA Goddard Space
Flight Ctr. (USA))
Publication: UV/Optical/IR Space Telescopes: Innovative
Technologies and Concepts III. Edited by MacEwen,
Howard A.; Breckinridge, James B. Proceedings of
the SPIE, Volume 6687, pp. 66870K-66870K-8 (2007).
Publication Date: 09/2007
Origin: SPIE
Abstract Copyright: (c) 2007: SPIE--The International Society for
Optical Engineering. Downloading of the abstract is
permitted for personal use only.
DOI: 10.1117/12.732833
Bibliographic Code: 2007SPIE.6687E..19M
Abstract
Stellar Imager (SI) will be a Space-Based telescope consisting of 20 to
30 separated apertures. It is designed for UV/Optical imaging of stellar
surfaces and asteroseismology. This report describes details of an
alternative optical design for the beam combiner, dubbed the Spatial
Frequency Remapper (SFR). It sacrifices the large field of view of the
Fizeau combiner. In return, spectral resolution is obtained with a
diffraction grating rather than an array of energy-resolving detectors.
The SFR design works in principle and has been implemented with MIRC at
CHARA for a small number of apertures. Here, we show the number of
optical surfaces can be reduced and the concept scales gracefully to the
large number of apertures needed for Stellar Imager. We also describe a
potential application of this spatial frequency remapping to improved
imaging with filled-aperture systems. For filled-aperture imaging, the
SFR becomes the core of an improved aperture masking system. To date,
aperture-masking has produced the best images with ground-based
telescopes but at the expense of low sensitivity due to short exposures
and the discarding of most of the light collected by the telescope. This
design eliminates the light-loss problem previously claimed to be
inherent in all aperture-masking designs. We also argue that at least in
principle, the short-integration time limit can also be overcome. With
these improvements, it becomes an ideal camera for TPF-C; since it can
form speckle-free images in the presence of wavefront errors, it should
significantly relax the stability requirements of the current designs.
Title: Wavefront sensing and closed-loop control for the
Fizeau interferometry testbed
Authors: Lyon, Richard G.; Carpenter, Kenneth G.; Liu, Alice;
Petrone, Peter; Dogoda, Peter; Reed, Daniel;
Mozurkewich, David
Affiliation: AA(NASA Goddard Space Flight Ctr. (USA)), AB(NASA
Goddard Space Flight Ctr. (USA)), AC(NASA Goddard
Space Flight Ctr. (USA)), AD(Sigma Space (USA)),
AE(Sigma Space (USA)), AF(Sigma Space (USA)),
AG(Seabrook Engineering (USA))
Publication: UV/Optical/IR Space Telescopes: Innovative
Technologies and Concepts III. Edited by MacEwen,
Howard A.; Breckinridge, James B. Proceedings of
the SPIE, Volume 6687, pp. 66870H-66870H-12 (2007).
Publication Date: 09/2007
Origin: SPIE
Abstract Copyright: (c) 2007: SPIE--The International Society for
Optical Engineering. Downloading of the abstract is
permitted for personal use only.
DOI: 10.1117/12.731761
Bibliographic Code: 2007SPIE.6687E..16L
Abstract
Stellar Imager (SI) is a proposed NASA space-based UV imaging
interferometer to resolve the stellar disks of nearby stars. SI would
consist of 20 - 30 separate spacecraft flying in formation at the
Earth-Sun L2 libration point. Onboard wavefront sensing and control is
required to maintain alignment during science observations and after
array reconfigurations. The Fizeau Interferometry Testbed (FIT),
developed at the NASA/Goddard Space Flight Center, is being used to
study wavefront sensing and control methodologies for Stellar Imager and
other large, sparse aperture telescope systems. FIT initially consists
of 7 articulated spherical mirrors in a Golay pattern, and is currently
undergoing expansion to 18 elements. FIT currently uses in-focus
whitelight sparse aperture PSFs and a direct solve phase retrieval
algorithm to sense and control its wavefront. Ultimately it will use
extended scene wavelength, with a sequential diversity algorithm that
modulates a subset of aperture pistons to jointly estimate the wavefront
and the reconstructed image from extended scenes. The recovered
wavefront is decomposed into the eigenmodes of the control matrix and
actuators are moved to minimize the wavefront piston, tip and tilt in
closed-loop. We discuss the testbed, wavefront control methodology and
ongoing work to increase its bandwidth from 1 per 11 seconds to a few
10's of Hertz and show ongoing results.
Title: Direct UV/optical imaging of stellar surfaces: the
Stellar Imager Vision Mission
Authors: Carpenter, Kenneth G.; Lyon, Richard G.;
Schrijver, Carolus; Karovska, Margarita;
Mozurkewich, David
Affiliation: AA(NASA-GSFC (USA)), AB(NASA-GSFC (USA)), AC(LMATC
(USA)), AD(SAO (USA)), AE(Seabrook Engineering
(USA))
Publication: UV/Optical/IR Space Telescopes: Innovative
Technologies and Concepts III. Edited by MacEwen,
Howard A.; Breckinridge, James B. Proceedings of
the SPIE, Volume 6687, pp. 66870G-66870G-12 (2007).
Publication Date: 09/2007
Origin: SPIE
Abstract Copyright: (c) 2007: SPIE--The International Society for
Optical Engineering. Downloading of the abstract is
permitted for personal use only.
DOI: 10.1117/12.732440
Bibliographic Code: 2007SPIE.6687E..15C
Abstract
The Stellar Imager (SI) is a UV/optical, space-based interferometer
designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar
surfaces and, via asteroseismology, stellar interiors and of the
Universe in general. SI's science focuses on the role of magnetism in
the Universe, particularly on magnetic activity on the surfaces of stars
like the Sun. SI's prime goal is to enable long-term forecasting of
solar activity and the space weather that it drives, in support of the
Living with a Star program in the Exploration Era. SI will also
revolutionize our understanding of the formation of planetary systems,
of the habitability and climatology of distant planets, and of many
magneto-hydrodynamically controlled processes in the Universe. SI is a
"Flagship and Landmark Discovery Mission" in the 2005 Sun Solar System
Connection (SSSC) Roadmap and a candidate for a "Pathways to Life
Observatory" in the Exploration of the Universe Division (EUD) Roadmap
(May, 2005). We discuss herein the science goals of the SI Mission, a
mission architecture that could meet those goals, and the technologies
needed to enable this mission. Additional information on SI can be found
at: http://hires.gsfc.nasa.gov/si/.
Title: Dynamos, Asteroseismology, and the Stellar Imager
Authors: Schrijver, C. J.; Carpenter, K. G.; Karovska, M.
Publication: Communications in Astroseismology, Vol. 150, p.364
Publication Date: 06/2007
Origin: AASP
DOI: 10.1553/cia150s364
Bibliographic Code: 2007CoAst.150..364S
Abstract
The ultra-sharp images of the Stellar Imager (SI) will revolutionize our
view of many dynamic astrophysical processes: The 0.1 milli-arcsec
resolution of this deep-space telescope will transform point sources
into extended sources, and simple snapshots into spellbinding evolving
views. SI's science focuses on the role of magnetism in the Universe,
particularly on magnetic activity on the surfaces of stars like the Sun
and on the subsurface flows that drive this activity. SI's prime goal is
to image magnetically active stars with enough resolution to map their
evolving dynamo patterns and their internal flows. By exploring the
Universe at ultra-high resolution, SI will also revolutionize our
understanding of the formation of planetary systems, of the habitability
and climatology of Earth as well as distant exoplanets, and of many
magneto-hydrodynamically controlled structures and processes in the
Universe.
See http://hires.gsfc.nasa.gov/si/ for details on the Stellar Imager
mission.
Title: Stellar Imager
Authors: Carpenter, Kenneth
Publication: Technical Report,
Publication Date: 02/2007
Category: Astrophysics
Origin: STI
NASA/STI Keywords: IMAGING TECHNIQUES, ASTROPHYSICS, INTERFEROMETERS,
FIZEAU EFFECT, ASTEROSEISMOLOGY, ULTRAVIOLET
RADIATION, STELLAR ACTIVITY, SUN, LAGRANGE
COORDINATES, CROSS SECTIONS, ANGULAR RESOLUTION,
STELLAR INTERIORS, SIMULATION, STELLAR ATMOSPHERES,
MAGNETIC VARIATIONS, POINT SOURCES, CLIMATE
Comment: NASA/STI Accession number: 20070034890
Bibliographic Code: 2007STIN...0734890C
Abstract
The Stellar Imager (SI) is one of NASA's "Vision Missions" - concepts
for future, space-based, strategic missions that could enormously
increase our capabilities for observing the Cosmos. SI is designed as a
UV/Optical Interferometer which will enable 0.1 milli-arcsecond (mas)
spectral imaging of stellar surfaces and, via asteroseismology, stellar
interiors and of the Universe in general. The ultra-sharp images of the
Stellar Imager will revolutionize our view of many dynamic astrophysical
processes by transforming point sources into extended sources, and
snapshots into evolving views. SI, with a characteristic angular
resolution of 0.1 milli-arcseconds at 2000 Angstroms, represents an
advance in image detail of several hundred times over that provided by
the Hubble Space Telescope. The Stellar Imager will zoom in on what
today-with few exceptions - we only know as point sources, revealing
processes never before seen, thus providing a tool as fundamental to
astrophysics as the microscope is to the study of life on Earth. SI's
science focuses on the role of magnetism in the Universe, particularly
on magnetic activity on the surfaces of stars like the Sun. It's prime
goal is to enable long-term forecasting of solar activity and the space
weather that it drives, in support of the Living With a Star program in
the Exploration Era. SI will also revolutionize our understanding of the
formation of planetary systems, of the habitability and climatology of
distant planets, and of many magneto-hydrodynamically controlled
processes in the Universe. Stellar Imager is included as a "Flagship and
Landmark Discovery Mission" in the 2005 Sun Solar System Connection
(SSSC) Roadmap and as a candidate for a "Pathways to Life Observatory"
in the Exploration of the Universe Division (EUD) Roadmap (May, 2005)
and as such is a candidate mission for the 2025-2030 timeframe. An
artist's drawing of the current "baseline" concept for SI is presented.
Title: Potential Biological Functions Emerging from the
Different Estrogen Receptors
Authors: Carpenter, K. D.; Korach, K. S.
Publication: Annals of the New York Academy of Sciences, vol.
1092, issue 1, pp. 361-373
Publication Date: 12/2006
Origin: CROSSREF
DOI: 10.1196/annals.1365.033
Bibliographic Code: 2006NYASA1092..361C
Abstract
Not Available
Title: Steps Toward a UV/Optical Interferometer in Space:
FIT & SIFFT
Authors: Carpenter, Kenneth G.; Lyon, R. G.; Liu, A.;
Dogoda, P.; Petrone, P.; Mozurkewich, D.; Miller, D.;
Mohan, S.; Stahl, P.
Affiliation: AA(NASA's GSFC), AB(NASA's GSFC), AC(NASA's GSFC),
AD(Sigma Space), AE(Sigma Space), AF(Seabrook Eng),
AG(MIT), AH(MIT), AI(NASA's MSFC)
Publication: 2007 AAS/AAPT Joint Meeting, American Astronomical
Society Meeting 209, \#164.01; Bulletin of the
American Astronomical Society, Vol. 38, p.1129
Publication Date: 12/2006
Origin: AAS
Abstract Copyright: (c) 2006: American Astronomical Society
Bibliographic Code: 2006AAS...20916401C
Abstract
We summarize the goals and result-to-date of a ROSES/APRA-sponsored
program to develop two of the major technologies needed to enable the
design and construction of future large baseline, space-based
Interferometric and Sparse Aperture Telescope missions (e.g., Stellar
Imager, Life Finder, Black Hole Imager, and Planet Imager). The Fizeau
Interferometer Testbed (FIT) is being used to develop and demonstrate
nm-level, closed-loop optical control of mirrors (i.e., control of tip,
tilt, piston, translation of array elements) and the overall system to
keep multiple beams in phase and optimize imaging of a Fizeau
interferometric system and to assess various image reconstruction
algorithms (phase diversity, clean, maximum entropy method, etc.) for
utility and accuracy. The Synthetic Imaging Formation Flying Testbed
(SIFFT) is, in parallel, being used to develop and demonstrate
algorithms for autonomous cm-level precision formation flying, which can
be combined in the future with the higher precision optical control
systems (e.g., those developed on the FIT) to fully enable synthetic
aperture imaging systems. The ultimate goal of this research is the
demonstration of closed-loop performance of a unified system which
combines formation flying and nm-level optical control systems (based on
analysis of the science data stream) to maintain phasing of a large
array of space-borne mirrors, as needed for missions like those listed
above, as well as smaller baseline Precursor missions that may pave the
path to the larger strategic missions.
Title: Heavy Element Abundances in the Photospheres of Cool
Supergiants
Authors: Wahlgren, Glenn M.; Lundqvist, M.; Carpenter, K. G.
Affiliation: AA(CUA/NASA-GSFC), AB(Lund Observatory, Sweden),
AC(NASA-GSFC)
Publication: 2007 AAS/AAPT Joint Meeting, American Astronomical
Society Meeting 209, \#93.04; Bulletin of the
American Astronomical Society, Vol. 38, p.1030
Publication Date: 12/2006
Origin: AAS
Abstract Copyright: (c) 2006: American Astronomical Society
Bibliographic Code: 2006AAS...209.9304W
Abstract
We report on a program to determine the chemical composition of massive,
cool supergiant photospheres. We concentrate on elements heavier than
the iron group, addressing the question of whether nuclear by-products
from the weak s-process have been brought to the surface by convective
processes. For massive stars, atoms with mass up to approximately A =
100 are thought to be formed by neutron capture via the weak s-process.
The abundances of these elements have been calculated by other
researchers to be a function of stellar mass.
Our initial work has concentrated on the identification of useful atomic
spectral lines at infrared wavelengths, where absorption from molecular
species is reduced relative to that at optical wavelengths for M-type
stars. Abundances are determined by synthetic spectrum fitting to line
profiles in high-resolution spectra.
We present results for the cool, supergiant Betelgeuse (M2 Iab).
Abundances are determined for a number of heavy elements, and despite
large uncertainties attributed to the available atomic data (oscillator
strengths), a distinct enhancement of Sr is determined after correcting
for non-LTE effects. Such an enhancement is predicted by models of
interior nucleosynthesis via neutron capture. Our results illuminate the
problems that must be overcome before being able to derive abundances
with the accuracy required for rigorous comparison with theoretical
calculations. We also present our approach to applying the results for
Betelgeuse to additional cool supergiants.
Title: The Stellar Imager (SI) vision mission
Authors: Carpenter, Kenneth G.; Schrijver, Carolus J.;
Karovska, Margarita
Affiliation: AA(NASA Goddard Space Flight Ctr. (USA)),
AB(Lockheed Martin Advanced Technology Ctr. (USA)),
AC(Smithsonian Astrophysical Observatory (USA))
Publication: Advances in Stellar Interferometry. Edited by
Monnier, John D.; Schöller, Markus; Danchi, William
C.. Proceedings of the SPIE, Volume 6268, pp.
626821 (2006).
Publication Date: 07/2006
Origin: SPIE
Abstract Copyright: (c) 2006: SPIE--The International Society for
Optical Engineering. Downloading of the abstract is
permitted for personal use only.
DOI: 10.1117/12.669713
Bibliographic Code: 2006SPIE.6268E..63C
Abstract
The Stellar Imager (SI) is a UV-Optical, Space-Based Interferometer
designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar
surfaces and of the Universe in general and asteroseismic imaging of
stellar interiors. SI is identified as a "Flagship and Landmark
Discovery Mission" in the 2005 Sun Solar System Connection (SSSC)
Roadmap and as a candidate for a "Pathways to Life Observatory" in the
Exploration of the Universe Division (EUD) Roadmap (May, 2005). SI will
revolutionize our view of many dynamic astrophysical processes: its
resolution will transform point sources into extended sources, and
snapshots into evolving views. SI's science focuses on the role of
magnetism in the Universe, particularly on magnetic activity on the
surfaces of stars like the Sun. SI's prime goal is to enable long-term
forecasting of solar activity and the space weather that it drives. SI
will also revolutionize our understanding of the formation of planetary
systems, of the habitability and climatology of distant planets, and of
many magneto-hydrodynamically controlled processes in the Universe. The
results of the SI "Vision Mission" Study are presented in this paper.
Additional information on the SI mission concept and related technology
development can be found at URL: http://hires.gsfc.nasa.gov/si/.
Title: Syntheses and catalytic activities of single-wall
carbon nanotubes-supported nickel (II)
metallacarboranes for olefin polymerization
Authors: Yinghuai, Zhu; Sia, Shirley Lo Pei; Carpenter, Keith;
Kooli, Fethi; Kemp, Richard A.
Affiliation: AA(Institute of Chemical and Engineering Sciences
Ltd, 1 Pesek Road, Jurong Island, Singapore 627833),
AB(Institute of Chemical and Engineering Sciences
Ltd, 1 Pesek Road, Jurong Island, Singapore 627833),
AC(Institute of Chemical and Engineering Sciences
Ltd, 1 Pesek Road, Jurong Island, Singapore 627833),
AD(Institute of Chemical and Engineering Sciences
Ltd, 1 Pesek Road, Jurong Island, Singapore 627833),
AE(Advanced Materials Laboratory, Sandia National
Laboratories, Albuquerque, NM 87106, USA; Department
of Chemistry, University of New Mexico, Albuquerque,
NM 87131-2609, USA)
Publication: Journal of Physics and Chemistry of Solids, Volume
67, Issue 5-6, p. 1218-1222.
Publication Date: 05/2006
Origin: ELSEVIER
Abstract Copyright: Elsevier Ltd
DOI: 10.1016/j.jpcs.2006.01.072
Bibliographic Code: 2006JPCS...67.1218Y
Abstract
Single-wall carbon nanotubes (SWCNTs)-supported nickel (II) carborane
complex,
([closo-1-Ni(PPh3)2-2-Me-3-((CH2)4NH-)-eta5-2,3-C2B9H9][OEt])n(SWCNT)
(3) has been synthesized by the reaction of in situ prepared
nido-C2B9-carborane-functionalized SWCNTs,
1)4NH-)-1,2-CBH10-][OEt])n(SWCNT)
(1) with dichlorobis(triphenylphosphine)nickel (II) (2). Reaction of
closo-1-Me-1,2-C2B10H11 (4) with
n-butyllithium followed by treatment with 1-bromopentane results in the
formation of
closo-1-Me-2-pentyl-1,2-C2B10H10 (5) in
91% yield. After decapitation of (5) with sodium hydroxide in refluxing
ethanol, the salt
Na[nido-7-Me-8-pentyl-7,8-C2B9H10] (6)
has been obtained in 77% yield. For the purpose of comparison of
catalytic activity, homogeneous analogue
closo-1-Ni(PPh3)2-2-Me-3-Pentyl-eta5-2,3-C2B9H9
(7) has been prepared in 83% from its nido-precursor (6). The above
synthesized nickel complexes (3) and (7) have been tested as moderately
active catalysts for olefin polymerization in the presence of the
co-catalyst MAO.
Title: SI - The Stellar Imager: Results from the Vision
Mission Study
Authors: Carpenter, K. G.; Schrijver, C. J.; Karovska, M.;
SI Vision Mission Study Team
Affiliation: AA(NASA-GSFC), AB(LMATC), AC(SAO)
Publication: American Astronomical Society Meeting 207, \#23.07;
Bulletin of the American Astronomical Society, Vol.
37, p.1196
Publication Date: 12/2005
Origin: AAS
Abstract Copyright: (c) 2005: American Astronomical Society
Bibliographic Code: 2005AAS...207.2307C
Abstract
The Stellar Imager (SI) is a UV-Optical, Space-Based Interferometer
designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar
surfaces and stellar interiors (via asteroseismology) and of the
Universe in general. SI was included as a "far horizon" or "Vision
Mission" in the 2000 and 2003 SEC Roadmaps and is now identified as a
"Flagship and Landmark Discovery Mission" in the 2005 Sun Solar System
Connection (SSSC) Roadmap and as a candidate for a "Pathways to Life
Observatory" in the Exploration of the Universe Division (EUD) Roadmap
(May, 2005). The ultra-sharp images of the Stellar Imager will
revolutionize our view of many dynamic astrophysical processes: The 0.1
mas resolution of this deep-space telescope will transform point sources
into extended sources, and snapshots into evolving views. SI's science
focuses on the role of magnetism in the Universe, particularly on
magnetic activity on the surfaces of stars like the Sun. SI's prime goal
is to enable long-term forecasting of solar activity and the space
weather that it drives in support of the Living With a Star program in
the Exploration Era. SI will also revolutionize our understanding of the
formation of planetary systems, of the habitability and climatology of
distant planets, and of many magneto-hydrodynamically controlled
processes in the Universe. The results of a just-concluded "Vision
Mission" Study of Stellar Imager will be presented in this paper.
This work was supported, in part, by Vision Mission Study grants from
NASA HQ to NASA-GSFC and from GSFC to Smithsonian Astrophysical
Observatory, Seabrook Engineering, SUNY/Stonybrook, U. Colorado/Boulder,
and STScI. Substantial complementary internal institutional support is
gratefully acknowledged from all of the participating institutions.
Title: High-Mass Triple Systems: The Classical Cepheid Y
Carinae
Authors: Evans, Nancy Remage; Carpenter, Kenneth G.;
Robinson, Richard; Kienzle, Francesco;
Dekas, Anne E.
Affiliation: AA(Smithsonian Astrophysical Observatory, 60 Garden
Street, Cambridge, MA 02138;
Center, Greenbelt, MD 20771;
University, Baltimore, MD 21218;
Sauverny, Switzerland;
College, Cambridge, MA 02138)
Publication: The Astronomical Journal, Volume 130, Issue 2, pp.
789-793.
Publication Date: 08/2005
Origin: UCP
AJ Keywords: Stars: Binaries: Close, Stars: Variables: Cepheids,
Stars: Evolution, Stars: Fundamental Parameters
Abstract Copyright: (c) 2005: The American Astronomical Society
DOI: 10.1086/430458
Bibliographic Code: 2005AJ....130..789E
Abstract
We have obtained a Hubble Space Telescope STIS ultraviolet
high-dispersion echelle-mode spectrum of the binary companion of the
double-mode classical Cepheid Y Car. The velocity measured for the hot
companion from this spectrum is very different from reasonable
predictions for binary motion, implying that the companion is itself a
short-period binary. The measured velocity changed by 7 km
s-1 during the 4 days between two segments of the
observation, confirming this interpretation. We summarize ``binary''
Cepheids that are in fact members of a triple system and find that at
least 44% are triples. The summary of information on Cepheids with
orbits makes it likely that the fraction is underestimated.
Based on observations made with the NASA/ESA Hubble Space Telescope,
obtained at the Space Telescope Science Institute, which is operated by
the Association of Universities for Research in Astronomy, Inc.
Title: Seasonal Phosphorus and Nitrogen Trends During
Restoration of the Wood River Wetland, Klamath
Falls, Oregon
Authors: Duff, J.; Carpenter, K.; Watkins, W.; Avanzino, R.;
Triska, F.
Affiliation: AA(U.S. Geological Survey, 345 Middlefield Road,
Menlo Park, CA 94025 United States;
SE Cherry Blossum Drive, Portland, OR 97216 United
Management, 2795 Anderson Ave, Klamath Falls, OR
AD(U.S. Geological Survey, 345 Middlefield Road,
Menlo Park, CA 94025 United States;
Middlefield Road, Menlo Park, CA 94025 United
Publication: American Geophysical Union, Spring Meeting 2005,
abstract \#NB33C-02
Publication Date: 05/2005
Origin: AGU
AGU Keywords: 1890 Wetlands
Bibliographic Code: 2005AGUSMNB33C..02D
Abstract
From 1985-1994, the 3200 acre Wood River Wetland (WRW) was managed as
irrigated pasture for beef cattle production. In 1996, a project to
restore the historical wetland was initiated to provide long-term
improvement in water quality and quantity entering Agency/Klamath Lake.
Presently, the WRW is managed for seasonal wetland habitat (1600 acres)
and more permanent marsh/open water habit (1400 acres). Between May and
August 2003, TP increased from 4 to 19 mg P/L. TP was significantly
higher in the wetland than in source waters, including artesian
groundwater and surface streams. TP increased at the same rate as
specific conductance, suggesting that the increase resulted from water
evaporation rather than biological or geochemical processes.
Approximately 75-95 percent of the TP was soluble inorganic P. TKN, like
TP, increased from 7 to 19 mg N/L and was significantly higher in the
wetland than in any potential source. TKN, unlike TP, consisted mainly
of an organic form of N, with 10 percent or less composed of ammonium
and nitrate. Since SRP dominated the TP pool, and concentrations were
exceedingly high, there was little biological impact on the P cycle. The
low concentrations of bioavailable N indicated a significant biological
impact on the inorganic N cycle.
Title: Assessment of Aquatic Biological Communities Along a
Gradient of Urbanization in the Willamette Valley
Ecoregion, Oregon and Washington.
Authors: Waite, I. R.; Arnsberg, A.; Carpenter, K. D.;
Rinella, F.; Sobieszczyk, S.; Wigger, I.;
Sarantou, M.
Affiliation: AA(U.S. Geological Survey Oregon Water Science
Center, 10615 S.E. Cherry Blossom Dr., Portland, OR
Geological Survey Oregon Water Science Center, 10615
S.E. Cherry Blossom Dr., Portland, OR 97216 United
States; ), AC(U.S. Geological Survey Oregon Water
Science Center, 10615 S.E. Cherry Blossom Dr.,
Portland, OR 97216 United States; ), AD(U.S.
Geological Survey Oregon Water Science Center, 10615
S.E. Cherry Blossom Dr., Portland, OR 97216 United
States; ), AE(U.S. Geological Survey Oregon Water
Science Center, 10615 S.E. Cherry Blossom Dr.,
Portland, OR 97216 United States; ), AF(U.S.
Geological Survey Oregon Water Science Center, 10615
S.E. Cherry Blossom Dr., Portland, OR 97216 United
States; ), AG(U.S. Geological Survey Oregon Water
Science Center, 10615 S.E. Cherry Blossom Dr.,
Portland, OR 97216 United States; )
Publication: American Geophysical Union, Spring Meeting 2005,
abstract \#NB22F-01
Publication Date: 05/2005
Origin: AGU
AGU Keywords: 1824 Geomorphology (1625)
Bibliographic Code: 2005AGUSMNB22F..01W
Abstract
From late 2003 through summer 2004, the U.S. Geological Survey's
National Water Quality Assessment Program sampled 28 streams within the
Willamette Basin to investigate effects of urbanization on aquatic
biology (fish, macroinvertebrates and algae), habitat, and water
chemistry. The 28 watersheds fall along an urban land use gradient index
(0 to 100, lowest to highest) based on land use and census data
developed for this region. Watershed areas range from 13 to 96 square
kilometers and contain greater than 20 percent of the Willamette Valley
ecoregion. Ten streams were sampled for water chemistry six times during
study period. The other 18 streams were sampled twice for water
chemistry-once during high sustained flow, and once during summer low
flow. The data will be analyzed to determine relationships to the urban
gradient index and for possible detection of threshold responses.
Preliminary results indicate that 57 percent of the most urbanized
streams contained nonnative fish species, but only 43 percent contained
salmonids. Conversely, nonnative fish species were present in 14 percent
of the least urbanized streams, whereas salmonids were present in 79
percent of these streams. Population density and water chemistry
variables were highly correlated with fish assemblage patterns among
sites.
Title: The Stellar Imager: a deep-space telescope to image
stellar surfaces
Authors: Schrijver, C. J.; Carpenter, K. G.; Karovska, M.;
The Si Vision Mission Team
Publication: Proceedings of the 13th Cambridge Workshop on Cool
Stars, Stellar Systems and the Sun, held 5-9 July,
2004 in Hamburg, Germany. Edited by F. Favata,
G.A.J. Hussain, and B. Battrick. ESA SP-560,
European Space Agency, 2005., p.951
Publication Date: 03/2005
Origin: ADS
Bibliographic Code: 2005ESASP.560..951S
Abstract
Not Available
Title: Stellar Imager (SI) Vision Mission Science Drivers
Authors: Karovska, M.; Carpenter, K. G.; Schrijver, C. J.;
SI Mission Concept Development
Affiliation: AA(Harvard-Smithsonian CfA), AB(GSFC), AC(LMATC)
Publication: American Astronomical Society Meeting 205, \#180.05;
Bulletin of the American Astronomical Society, Vol.
37, p.384
Publication Date: 12/2004
Origin: AAS
Abstract Copyright: (c) 2004: American Astronomical Society
Bibliographic Code: 2004AAS...20518005K
Abstract
We describe the key scientific drivers for the Stellar Imager (SI)
Vision Mission - a UV-optical 0.1 milli-arcsecond (mas) imaging space
interferometer. Ultra-high sub-mas angular resolution imaging at UV and
optical wavelengths is key to studies of magnetic field structures that
govern the formation of stars and planetary systems, the habitability of
planets, long-term space weather in the Exploration era, and transport
processes on many scales in the Universe. Magnetic fields affect the
evolution of structure in the Universe and drive solar and stellar
activity which is a key to life's origin and survival. However, our
understanding of how magnetic fields form, operate, and evolve is
currently very limited, even for the nearest star, our Sun.
The key science goal of the Stellar Imager Mission is to obtain an
understanding of stellar dynamos, and in particular the solar dynamo,
through a population study of other stars representing a broad range of
stellar parameters and activity. The end goal is to understand the
variable impact of stellar magnetic activity on planetary climates and
the origin and maintenance of life. Improved knowledge of solar-type
dynamo activity and the interaction of global fields and flows is also
crucial for developing models for long-term space weather forcasting.
Furthermore, SI's high-angular resolution capabilities, over two
magnitudes better then the HST, will enable unprecedented studies of
dynamo and accretion-driven processes, and mass exchange and mass flows
in a wide variety of galactic and extragalactic sources, including young
star/disk systems, solar-type and evolved stars and astrospheres,
numerous interacting binaries, and SN, AGN, and black hole environments.
Title: Planetary Environment Study at Sub-milliarcsecond
Resolution
Authors: Ragozzine, D.; Karovska, M.; Hartmann, L.;
Sasselov, D.; Carpenter, K.; SI
Affiliation: AA(CfA & Caltech), AB(CfA), AC(CfA), AD(CfA),
AE(GSFC)
Publication: American Astronomical Society Meeting 205, \#17.18;
Bulletin of the American Astronomical Society, Vol.
36, p.1368
Publication Date: 12/2004
Origin: AAS
Abstract Copyright: (c) 2004: American Astronomical Society
Bibliographic Code: 2004AAS...205.1718R
Abstract
The Stellar Imager (SI; http://hires.gsfc.nasa.gov/ ˜si ) is a
NASA Vision Mission, conceived of as a space-based UV-Optical
long-baseline interferometer that will provide sub-milliarcsecond
imaging capabilities. We present results from our study of how SI could
be used to answer key questions about planet formation and
planet-star-disk interactions. SI would be able to resolve and
characterize star-disk interactions at a few stellar radii, including
accretion and inner disk edge heating. Simple models of T-Tauri stars
are used to probe SI's sensitivity to various critical parameters and
geometries. By observing H2-flourescent lines in the UV, the contrast
between the luminosity of the star and the gas can be improved. A list
of potential targets among known planet-harboring stars is also
presented with the hope of resolving possible star-planet interactions.
Acknowledgement: This work was supported by the SI Vision Mission study
grant NNG04GM92G from NASA/GSFC to SAO. MK is a member of the Chandra
X-ray Center (NASA contract NAS8-39073).
Title: The Stellar Imager (SI): Preliminary Results from
the Ongoing Vision Mission Study
Authors: Carpenter, K. G.; Schrijver, C. J.;
SI Mission Concept Development
Affiliation: AA(NASA's GSFC), AB(LMATC)
Publication: American Astronomical Society Meeting 205, \#05.09;
Bulletin of the American Astronomical Society, Vol.
36, p.1342
Publication Date: 12/2004
Origin: AAS
Abstract Copyright: (c) 2004: American Astronomical Society
Bibliographic Code: 2004AAS...205.0509C
Abstract
The Stellar Imager (SI) is a "Vision Mission" in the far-horizon NASA
Roadmap, conceived for the purpose of understanding the effects of
stellar magnetic fields, the dynamos that generate them, and the
internal structure and dynamics of the stars in which they exist. The
ultimate goal is to achieve the best possible forecasting of
solar/stellar activity and to understand the impact of that activity on
planetary climates and the origin and maintenance of life in the
Universe. The science goals of SI require an ultra-high angular
resolution, at ultraviolet wavelengths, on the order of 100 micro-arcsec
and baselines on the order of 0.5 km. SI's resolution will make it an
invaluable resource for many other areas of astrophysics, including
studies of AGN's, supernovae, cataclysmic variables, young stellar
objects, QSO's, and stellar black holes. These requirements call for a
large, multi-spacecraft (>20) imaging interferometer, utilizing
precision formation flying in a stable environment, such as in a
Lissajous orbit around the Sun-Earth L2 point. In this paper, we present
an update on the ongoing SI Vision Mission concept and technology
development studies.
The SI Mission Concept Study is supported, in part, by grants from
NASA-HQ through the 2003 Vision Mission NRA.
Title: Fabrication and characterization of the Fizeau
interferometer testbed
Authors: Petrone, Peter, III; Carpenter, Kenneth G.;
Clark, Dave; Cottle, Paul; Dogoda, Peter;
Huet, Hubert; Liiva, Peter; Lyon, Richard G.;
Marzouk, Joe; Mazzuca, Lisa M.; McAndrew, Dave;
Solyar, Gregory
Publication: New Frontiers in Stellar Interferometry, Proceedings
of SPIE Volume 5491. Edited by Wesley A. Traub.
Bellingham, WA: The International Society for
Optical Engineering, 2004., p.1776
Publication Date: 10/2004
Origin: ADS
Bibliographic Code: 2004SPIE.5491.1776P
Abstract
The Fizeau Interferometer Testbed (FIT) is a ground-based system that
will be used for the development and testing of technologies relevant to
Stellar Imager (SI) and other sparse aperture/Fizeau imaging
interferometer mission concepts. The testbed will utilize image-based
wavefront sensing and control to co-phase and maintain closed-loop
control over a Sparse Aperture Array (SAA) consisting of spherical
mirror elements. The SAA is a re-configurable assembly baselined to
incorporate between seven (initially) and thirty 12.5mm diameter (R =
4000mm) mirror elements. In this paper we describe the fabrication,
alignment, and initial calibration of the phase I (7 primary elements)
FIT hardware and discuss various factors impacting the performance and
stability of the testbed.
Title: The Fizeau interferometer testbed (FIT): developing
and testing the technologies needed for space-based
interferometric imaging systems
Authors: Mazzuca, Lisa M.; Carpenter, Kenneth G.;
Lyon, Richard G.; Marzouk, Joe; Petrone, Peter, III;
Cottle, Paul; Dogoda, Peter; Huet, Hubert;
Liiva, Peter; Mozurkewich, David; Armstrong, J. T.;
Zhang, Xiaolei; Solyar, Gregory; Mundy, Lee G.
Publication: New Frontiers in Stellar Interferometry, Proceedings
of SPIE Volume 5491. Edited by Wesley A. Traub.
Bellingham, WA: The International Society for
Optical Engineering, 2004., p.1034
Publication Date: 10/2004
Origin: ADS
Bibliographic Code: 2004SPIE.5491.1034M
Abstract
The Fizeau Interferometer Testbed (FIT) is a ground-based laboratory
experiment at Goddard Space Flight Center (GSFC) designed to develop and
test technologies that will be needed for future interferometric
spacecraft missions. Specifically, the research from this experiment is
a proof-of-concept for optical accuracy and stability, closed-loop
control algorithms, optimal sampling methodology of the Fourier
UV-plane, computational models for system performance, and image
synthesis techniques for a sparse array of 7 to 30 mirrors. It will
assess and refine the technical requirements on hardware, control, and
imaging algorithms for the Stellar Imager (SI), its pathfinder mission,
and other sparse aperture and interferometric imaging mission concepts.
This ground-based optical system is a collaborative effort between
NASA's GSFC, Sigma Space Corporation, the Naval Research Laboratory, and
the University of Maryland. We present an overview of the FIT design
goals and explain their associated validation methods. We further
document the design requirements and provide a status on their
completion. Next, we show the overall FIT design, including the optics
and data acquisition process. We discuss the technologies needed to
insure success of the testbed as well as for an entire class of future
mission concepts. Finally, we compare the expected performance to the
actual performance of the testbed using the initial array of seven
spherical mirrors. Currently, we have aligned and phased all seven
mirrors, demonstrated excellent system stability for extended periods of
time, and begun open-loop operations using "pinhole" light sources.
Extended scenes and calibration masks are being fabricated and will
shortly be installed in the source module. Installation of all the
different phase retrieval/diversity algorithms and control software is
well on the way to completion, in preparation for future tests of
closed-loop operations.
Title: Metrology and pointing for astronomical
interferometers
Authors: Phillips, James D.; Carpenter, Kenneth G.;
Gendreau, Keith C.; Karovska, Margarita;
Kaaret, Philip E.; Reasenberg, Robert D.
Publication: New Frontiers in Stellar Interferometry, Proceedings
of SPIE Volume 5491. Edited by Wesley A. Traub.
Bellingham, WA: The International Society for
Optical Engineering, 2004., p.320
Publication Date: 10/2004
Origin: ADS
Bibliographic Code: 2004SPIE.5491..320P
Abstract
Metrology and pointing will be enabling technologies for a new
generation of astronomical missions having large and distributed
apertures and delivering unprecedented performance. The UV
interferometer Stellar Imager would study stellar dynamos by imaging
magnetic activity on the disks of stars in our Galaxy. The X-ray
interferometer Black Hole Imager would study strong gravity physics and
the formation of jets by imaging the event horizons of supermassive
black holes. These missions require pointing to microarcseconds or
better, and metrology to nm accuracy of optical elements separated by
km, for control of optical path difference. This paper describes a
metrology and pointing system that meets these requirements for the
Stellar Imager. A reference platform uses interferometers to sense
alignment with a guide star. Laser gauges determine mirror positions in
the frame of the reference platform, and detector position is monitored
by laser gauges or observations of an artificial star. Applications to
other astronomical instruments are discussed.
Title: The Stellar Imager (SI): a revolutionary
large-baseline imaging interferometer at the
Sun-Earth L2 point
Authors: Carpenter, Kenneth G.; Schrijver, Carolus J.;
Allen, Ronald J.; Brown, Alexander; Chenette, David;
Danchi, William C.; Karovska, Margarita;
Kilston, Steven; Lyon, Richard G.; Marzouk, Joe;
Mazzuca, Lisa M.; Moe, Rud V.; Walter, Frederick;
Murphy, Neil
Publication: New Frontiers in Stellar Interferometry, Proceedings
of SPIE Volume 5491. Edited by Wesley A. Traub.
Bellingham, WA: The International Society for
Optical Engineering, 2004., p.243
Publication Date: 10/2004
Origin: ADS
Bibliographic Code: 2004SPIE.5491..243C
Abstract
The Stellar Imager (SI) is a far-horizon or "Vision" mission in the NASA
Sun-Earth Connection (SEC) Roadmap, conceived for the purpose of
understanding the effects of stellar magnetic fields, the dynamos that
generate them, and the internal structure and dynamics of the stars in
which they exist. The ultimate goal is to achieve the best possible
forecasting of solar/stellar activity and its impact on life in the
Universe. The science goals of SI require an ultra-high angular
resolution, at ultraviolet wavelengths, on the order of 0.1 milliarcsec
and thus baselines on the order of 500 meters. These requirements call
for a large, multi-spacecraft (>20) imaging interferometer, utilizing
precision formation flying in a stable environment, such as in a
Lissajous orbit around the Sun-Earth L2 point. SI's resolution (several
100 times that of HST) will make it an invaluable resource for many
other areas of astrophysics, including studies of AGN's, supernovae,
cataclysmic variables, young stellar objects, QSO's, and stellar black
holes. In this paper, we present an update on the ongoing mission
concept and technology development studies for SI. These studies are
designed to refine the mission requirements for the science goals,
define a Design Reference Mission, perform trade studies of selected
major technical and architectural issues, improve the existing
technology roadmap, and explore the details of deployment and
operations, as well as the possible roles of astronauts and/or robots in
construction and servicing of the facility.
Title: Apodized square aperture plus occulter concept for
TPF
Authors: Jordan, Ian J. E.; Schultz, Alfred B.;
Lyon, Richard G.; Hart, Helen M.;
Bruhweiler, Frederick; Fraquelli, Dorothy A.;
Carpenter, Kenneth G.; Kochte, Mark; Hollis, Jan M.
Affiliation: AA(Computer Sciences Corp. (USA) and Space Telescope
Science Institute (USA)), AB(Computer Sciences Corp.
(USA) and Space Telescope Science Institute (USA)),
AC(NASA Goddard Space Flight Ctr. (USA)),
AD(Computer Sciences Corp. (USA) and Johns Hopkins
Univ. (USA)), AE(Institute for Astrophysics and
Computational Sciences (USA)), AF(Computer Sciences
Corp. (USA) and Space Telescope Science Institute
(USA)), AG(NASA Goddard Space Flight Ctr. (USA)),
AH(Computer Sciences Corp. (USA) and Space Telescope
Science Institute (USA)), AI(NASA Goddard Space
Flight Ctr. (USA))
Publication: Optical, Infrared, and Millimeter Space Telescopes.
Edited by Mather, John C. Proceedings of the
SPIE, Volume 5487, pp. 1391-1401 (2004).
Publication Date: 10/2004
Origin: SPIE
Abstract Copyright: (c) 2004: SPIE--The International Society for
Optical Engineering. Downloading of the abstract is
permitted for personal use only.
DOI: 10.1117/12.553029
Bibliographic Code: 2004SPIE.5487.1391J
Abstract
The standard approach to achieving TPF-level starlight suppression has
been to couple a few techniques together. Deployment of a low- or
medium-performance external occulter as the first stage of starlight
suppression reduces manufacturing challenges, mitigates
under-performance risks, lowers development costs, and hastens launch
date for TPF. This paper describes the important aspects of a conceptual
4-metre apodized square aperture telescope system utilizing a
low-performance external occulter. Adding an external occulter to such a
standard TPF design provides a benefit that no other technique offers:
scattered and diffracted on-axis starlight is suppressed by orders of
magnitude before reaching the telescope. This translates directly into
relaxed requirements on the remainder of the optical system.
Title: Fizeau interferometry testbed: wavefront control
Authors: Lyon, Richard G.; Carpenter, Kenneth G.;
Mazzuca, Lisa; Huet, Hubert; Cottle, Paul W.;
Petrone, Peter P., III; Dagoda, Peter; Liiva, Peter;
Marzouk, Joe; Solyar, Gregory; Mozurkewich, David;
Zhang, Xiaolei; Armstrong, Thomas
Affiliation: AA(NASA Goddard Space Flight Ctr. (USA)), AB(NASA
Goddard Space Flight Ctr. (USA)), AC(NASA Goddard
Space Flight Ctr. (USA)), AD(Sigma Space Corp.
(USA)), AE(Sigma Space Corp. (USA)), AF(Sigma Space
Corp. (USA) and NASA Goddard Space Flight Ctr.
(USA)), AG(Sigma Space Corp. (USA) and NASA Goddard
Space Flight Ctr. (USA)), AH(Sigma Space Corp.
(USA)), AI(Sigma Space Corp. (USA)), AJ(Univ. of
Maryland/Baltimore County (USA)), AK(Seabrook
Engineering (USA)), AL(Naval Research Lab. (USA)),
AM(Naval Research Lab. (USA))
Publication: Optical, Infrared, and Millimeter Space Telescopes.
Edited by Mather, John C. Proceedings of the
SPIE, Volume 5487, pp. 963-974 (2004).
Publication Date: 10/2004
Origin: SPIE
Abstract Copyright: (c) 2004: SPIE--The International Society for
Optical Engineering. Downloading of the abstract is
permitted for personal use only.
DOI: 10.1117/12.552198
Bibliographic Code: 2004SPIE.5487..963L
Abstract
Stellar Imager (SI) is a potential NASA space-based UV imaging
interferometer to resolve the stellar disks of nearby stars. SI would
consist of 20 - 30 separate spacecraft flying in formation at the
Earth-Sun L2 libration point. Onboard wavefront control would be
required to initially align the formation and maintain alignment during
science observations and after array reconfiguration. The Fizeau
Interferometry Testbed (FIT) is a testbed currently under development at
the NASA/Goddard Space Flight Center to develop and study the wavefront
control methodologies for Stellar Imager and other large, sparse
aperture telescope systems. FIT consists of 7 articulated spherical
mirrors in a Golay pattern, expandable up to 30 elements, and
reconfigurable into multiple array patterns. FIT"s purpose is to
demonstrate image quality versus array configuration and to develop and
advance the wavefront control for SI. FIT uses extended scene
wavelength, focus and field diversity to estimate the wavefront across
the set of apertures. The recovered wavefront is decomposed into the
eigenmodes of the control matrix and actuators are moved to minimize the
wavefront piston, tip and tilt. Each mirror"s actuators are 3 degrees of
freedom, however, they do not move each of the mirrors about a point on
each mirrors surface, thus the mapping from wavefront piston, tip/tilt
to mirror piston, tip/tilt is not diagonal. We initially estimate this
mapping but update it as part of wavefront sensing and control process
using system identification techniques. We discuss the FIT testbed,
wavefront control methodology, and show initial results from FIT.
Title: Propagation of PAMAM Dendrons on Silica Gel: A Study
on the Reaction Kinetics
Authors: Bu, Jie; Li, Ruijiang; Quah, Chee Wee;
Carpenter, Keith J.
Publication: Macromolecules, vol. 37, issue 18, pp. 6687-6694
Publication Date: 09/2004
Origin: CROSSREF
DOI: 10.1021/ma040055b
Bibliographic Code: 2004MaMol..37.6687B
Abstract
Not Available
Title: Imaging Terrestrial Planets
Authors: Kochte, M.; Schultz, A. B.; Fraquelli, D.;
Jordan, I. J. E.; Lyon, R. G.; Carpenter, K. G.;
Hart, H. M.; Disanti, M.; Bruhweiler, F.; Miskey, C.;
Rodrigue, M.; Fadali, M. S.; Skelton, D.;
Cheng, K.-P.
Affiliation: AA(Computer Sciences Corporation, Space Telescope
Science Institute), AB(Computer Sciences
Corporation, Space Telescope Science Institute),
AC(Computer Sciences Corporation, Space Telescope
Science Institute), AD(Computer Sciences
Corporation, Space Telescope Science Institute),
AE(Goddard Space Flight Center/NASA), AF(Goddard
Space Flight Center/NASA), AG(Computer Sciences
Corporation, FUSE Project, JHU), AH(Goddard Space
Flight Center/NASA), AI(Catholic University of
America), AJ(Catholic University of America),
AK(University of Nevada), AL(University of Nevada),
AM(Optical Sciences Corporation), AN(California
State University, Fullerton)
Publication: THE SEARCH FOR OTHER WORLDS: Fourteenth Astrophysics
Conference. AIP Conference Proceedings, Volume 713,
pp. 223-226 (2004).
Publication Date: 06/2004
Origin: STI
Keywords: extrasolar planets, imaging, stars
Abstract Copyright: (c) 2004: American Institute of Physics
DOI: 10.1063/1.1774528
Bibliographic Code: 2004AIPC..713..223K
Abstract
We present optical simulations of a new approach to directly image
terrestrial planets. Terrestrial planets typically are 10 orders of
magnitude fainter than the central star, a difficult challenge for any
optical system. Our studies show that the combination of an external
occulter and an apodizer yields the required contrast, with
significantly reduced requirements on stray light and diffraction. This
mitigates the very high mirror tolerances required of other
coronagraphic methods and makes exo-planet detection feasible with
current technology.
Title: The O VI and C III Lines at 1032 and 977 Å in Hyades
F Stars
Authors: Böhm-Vitense, Erika; Robinson, Richard D.;
Carpenter, Kenneth G.
Affiliation: AA(Astronomy Department, University of Washington,
P.O. Box 351580, Seattle, WA 98195), AB(Institute
for Astrophysics and Computational Sciences and
Department of Physics, Catholic University of
America, Washington, DC 20064), AC(Laboratory for
Astronomy and Solar Physics, Code 681, NASA Goddard
Space Flight Center, Greenbelt, MD 20771)
Publication: The Astrophysical Journal, Volume 606, Issue 2, pp.
1174-1183.
Publication Date: 05/2004
Origin: UCP
ApJ Keywords: Galaxy: Open Clusters and Associations: Individual:
Name: Hyades, Stars: Coronae, Ultraviolet: Stars
Abstract Copyright: (c) 2004: The American Astronomical Society
DOI: 10.1086/383021
Bibliographic Code: 2004ApJ...606.1174B
Abstract
We continue our investigations into the mechanisms heating the outer
layers of cool dwarf stars. In this study we specifically seek to
determine whether in the layers with temperatures around 250,000-300,000
K, in which the O VI lines are emitted, the temperatures are determined
by heat conduction from the coronae or by the same processes that heat
the lower temperature regions. To study this we discuss here 22 spectra
of Hyades F stars taken by the Far Ultraviolet Spectroscopic Explorer
(FUSE) satellite to study the O VI lines at 1032 Å and the C III
lines at 977 Å and compare them with other lower transition layer
lines, observed with HST and IUE, and with existing X-ray data. For our
targets with B-V>0.4, the X-ray fluxes of single F stars increase, on
average, slowly with increasing B-V, while the O VI line fluxes show the
same steep decrease around B-V=0.43 as previously found for the lower
temperature transition layer lines. For single stars the X-ray fluxes
decrease with increasing vsini, except for the stars with B-V between
0.418 and 0.455, while for the O VI lines, as for the other transition
layer lines, fluxes increase with increasing vsini, if vsini is larger
than 30 km s-1. For smaller vsini, line fluxes are
independent of vsini. The B-V and vsini dependences of the O VI line
fluxes are then very different from those of the X-ray fluxes. We thus
conclude that for electron temperature Te below 300,000 K,
the transition layers for Hyades F stars are not mainly heated by heat
conduction from their coronae.
Based on observations made with the NASA-CNES-CSA Far Ultraviolet
Spectroscopic Explorer (FUSE) telescope, which is operated for NASA by
Johns Hopkins University, under contract NAS5-32985.
Title: The Fizeau Interferometer Testbed (FIT): Developing
and Testing the Technologies Needed for Space-Based
Interferometric Imaging Systems
Authors: Mazzuca, L. M.; Carpenter, K. G.; Lyon, R. G.;
Marzouk, J.; Cottle, P.; Dogoda, P.; Huet, H.;
Liiva, P.; Petrone, P.; Armstrong, J. T.; Zhang, X.;
Mundy, L.; Mozurkewich, D.; Solyar, G.
Affiliation: AA(NASA GSFC), AB(NASA GSFC), AC(NASA GSFC),
AD(Sigma Space Corp.), AE(Sigma Space Corp.),
AF(Sigma Space Corp.), AG(Sigma Space Corp.),
AH(Sigma Space Corp.), AI(Sigma Space Corp.),
AJ(NRL), AK(NRL), AL(University of Maryland),
AM(Seabrook Engineering), AN(GEST UMBC)
Publication: American Astronomical Society Meeting 204, \#08.12;
Bulletin of the American Astronomical Society, Vol.
36, p.791
Publication Date: 05/2004
Origin: AAS
Abstract Copyright: (c) 2004: American Astronomical Society
Bibliographic Code: 2004AAS...204.0812M
Abstract
The Fizeau Interferometer Testbed (FIT) is a ground-based laboratory
experiment at Goddard Space Flight Center (GSFC) designed to develop and
test technologies that will be needed for future interferometric
spacecraft missions. Specifically, the research from this experiment is
a proof-of-concept for optical accuracy and stability, closed-loop
control algorithms, optimal sampling methodology of the Fourier
UV-plane, computational models for system performance, and image
synthesis techniques for a sparse array of 7 to 30 mirrors. It will
assess and refine the technical requirements on hardware, control, and
imaging algorithms for the Stellar Imager (SI), its pathfinder mission,
and other sparse aperture and interferometric imaging mission concepts.
This ground-based optical system is a collaborative effort between
NASA's GSFC, Sigma Space Corporation, the Naval Research Laboratory, and
the University of Maryland. We present an overview of the final optical
design, detector system, and data acquisition process. We further
compare the expected performance to the actual performance of the
testbed using the initial array of seven spherical mirrors. Currently,
we have aligned and phased all seven mirrors, demonstrated excellent
system stability for extended periods of time, and begun open-loop
operations using "pinhole" light sources. Extended scenes and
calibration masks are being fabricated and will shortly be installed in
the source module. Installation of all the different phase
retrieval/diversity algorithms and control software is well on the way
to completion, in preparation for future tests of closed-loop
operations.
Title: The Stellar Imager (SI) ``Vision Mission"
Authors: Carpenter, K.; Danchi, W.; Leitner, J.; Liu, A.;
Lyon, R.; Mazzuca, L.; Moe, R.; Chenette, D.;
Schrijver, C.; Kilston, S.; Karovska, M.; Allen, R.;
Brown, A.; Marzouk, J.; Murphy, N.; Walter, F.
Affiliation: AA(NASA-GSFC), AB(NASA-GSFC), AC(NASA-GSFC),
AD(NASA-GSFC), AE(NASA-GSFC), AF(NASA-GSFC),
AG(NASA-GSFC), AH(LMATC), AI(LMATC), AJ(BATC),
AK(SAO), AL(STScI), AM(UCO), AN(Sigma Sp.), AO(JPL),
AP(SUNY)
Publication: American Astronomical Society Meeting 204, \#08.10;
Bulletin of the American Astronomical Society, Vol.
36, p.791
Publication Date: 05/2004
Origin: AAS
Abstract Copyright: (c) 2004: American Astronomical Society
Bibliographic Code: 2004AAS...204.0810C
Abstract
The Stellar Imager (SI) is a `Vision' mission in the Sun-Earth
Connection (SEC) Roadmap, conceived for the purpose of understanding the
effects of stellar magnetic fields, the dynamos that generate them, and
the internal structure and dynamics of the stars in which they exist.
The ultimate goal is to achieve the best possible forecasting of
solar/stellar magnetic activity and its impact on life in the Universe.
The science goals of SI require an ultra-high angular resolution, at
ultraviolet wavelengths, on the order of 100 micro-arcsec and thus
baselines on the order of 0.5 km. These requirements call for a large,
multi-spacecraft (>20) imaging interferometer, utilizing precision
formation flying in a stable environment, such as in a Lissajous orbit
around the Sun-Earth L2 point. SI's resolution will make it an
invaluable resource for many other areas of astrophysics, including
studies of AGN's, supernovae, cataclysmic variables, young stellar
objects, QSO's, and stellar black holes.
We present here an overview of the ongoing mission concept and
technology development studies for SI. These studies are designed to
refine the mission requirements for the science goals, define a Design
Reference Mission, perform trade studies of selected major technical and
architectural issues, improve the existing technology roadmap, and
explore the details of deployment and operations, as well as the
possible roles of astronauts and/or robots in construction and servicing
of the facility. Additional information on SI mission concepts and
technology can be found at URL: http://hires.gsfc.nasa.gov/ ˜si.
The SI Mission Concept Study is supported, in part, by grants from
NASA-HQ through the 2003 Vision Mission NRA.
Title: A hydroarchive for the free exchange of hydrological
software Website:
Authors: Wagener, Thorsten; Gupta, Hoshin V.; Carpenter, Kyle;
James, Brad; Vázquez, Ramón; Sorooshian, Soroosh;
Shuttleworth, Jim
Publication: Hydrological Processes, vol. 18, Issue 2, pp.389-391
Publication Date: 02/2004
Origin: WEB
DOI: 10.1002/hyp.5216
Bibliographic Code: 2004HyPr...18..389W
Abstract
Available from http://www3.interscience.wiley.com/cgi-bin/abstract/107063993/
Title: Redescription of Ankylosaurus magniventris Brown
1908 (Ankylosauridae) from the Upper Cretaceous of
the Western Interior of North America
Authors: Carpenter, Kenneth
Publication: Canadian Journal of Earth Sciences, vol. 41, issue
8, pp. 961-986
Publication Date: 00/2004
Origin: CROSSREF
DOI: 10.1139/e04-043
Bibliographic Code: 2004CaJES..41..961C
Abstract
Not Available
Title: Measured Cepheid Masses: U Aql
Authors: Evans, N. R.; Carpenter, K. C.; Robinson, R.;
Kienzle, F.; Albrow, M.
Affiliation: AA(SAO), AB(NASA's GSFC), AC(Johns Hopkins Univ.),
AD(Geneva Obs), AE(Univ. of Canterbury)
Publication: American Astronomical Society Meeting 203, \#84.10;
Bulletin of the American Astronomical Society, Vol.
35, p.1342
Publication Date: 12/2003
Origin: AAS
Abstract Copyright: (c) 2003: American Astronomical Society
Bibliographic Code: 2003AAS...203.8410E
Abstract
We have obtained an HST STIS ultraviolet high dispersion Echelle mode
spectrum of the companion of classical Cepheid U Aql. We have
cross-correlated it with a comparable spectrum of a velocity standard
(HD 72660) to obtain the velocity difference between the two. We have
been able to obtain a velocity signal with the relatively weak S/N, and
have had the best results when wavelength regions as large as 40 Å
have been used so that a pattern of features is available in each
spectrum. Combining the velocity amplitude of the Cepheid from the
ground-based orbit, the orbital velocity of the companion at the phase
of HST observation, and the mass of the companion inferred from an IUE
low resolution spectrum (1998, ApJ, 484, 768), we have obtained the mass
of the Cepheid itself. This work was supported in part by HST grant
HST-GO-09146.01-A and by NASA Contract NAS8-39073 to the Chandra X-ray
Center.
Title: Surprising Differences in the Winds and Mass-Loss
Rates of Two M-Giant Stars: Gamma Cru (M3.5III) and
Mu Gem (M3III)
Authors: Carpenter, K. G.; Robinson, R. D.
Affiliation: AA(NASA's GSFC), AB(JHU)
Publication: American Astronomical Society Meeting 203, \#49.02;
Bulletin of the American Astronomical Society, Vol.
35, p.1284
Publication Date: 12/2003
Origin: AAS
Abstract Copyright: (c) 2003: American Astronomical Society
Bibliographic Code: 2003AAS...203.4902C
Abstract
We have assessed important parameters of the stellar winds of two very
similar M giant stars, Gamma Cru (M3.5III) and Mu Gem (M3III), using
high resolution HST/GHRS spectra and found surprising differences in the
characteristics of their winds and in their total mass-loss rates. The
wind parameters, including flow and turbulent velocities, the optical
depth of the wind above the region of photon creation, and the mass-loss
rate, have been estimated by fitting line profiles computed using the
"Sobolev with Exact Integration" (SEI) radiative transfer code (Lamars
et al. 1987), along with simple models of the outer atmospheric
structure and wind. These computed profiles are fit to chromospheric
emission lines which show self-absorptions produced by the
photon-scattering winds of these stars. The SEI code has the advantage
of being computationally fast and allows a great number of possible wind
models to be examined. The analysis is iterative in nature: we specify
estimates of the wind parameters, calculate line profiles for the Mg II
(UV1) lines and a range of unblended Fe II lines (which have a wide
range of wind opacities and therefore probe different heights in the
atmosphere), compare the computed profiles with the observations, and
modify the assumed wind properties until the predicted profiles match
the observations over as many lines as possible.. Surprisingly, we find
that the Gamma Cru wind exhibits a significantly higher terminal
velocity, wind turbulence, and mass-loss rate than its fellow M-giant Mu
Gem.
Title: Imaging terrestrial planets with a free-flying
occulter and space telescope: an optical simulation
Authors: Schultz, Alfred B.; Lyon, Richard G.; Kochte, Mark;
Fraquelli, Dorothy A.; Bruhweiler, Frederick;
Jordan, Ian J. E.; Carpenter, Kenneth G.;
DiSanti, Michael A.; Miskey, Cherie;
Rodrigue, Melodi; Fadali, M. S.; Skelton, Dennis;
Hart, Helen M.; Cheng, Kwang-Ping
Affiliation: AA(Computer Sciences Corp. (USA) and Space Telescope
Science Institute (USA)), AB(NASA Goddard Space
Flight Ctr. (USA)), AC(Computer Sciences Corp. (USA)
and Space Telescope Science Institute (USA)),
AD(Computer Sciences Corp. (USA)), AE(Catholic Univ.
of America (USA)), AF(Computer Sciences Corp.
(USA)), AG(NASA Goddard Space Flight Ctr. (USA)),
AH(NASA Goddard Space Flight Ctr. (USA)),
AI(Catholic Univ. of America (USA)), AJ(Univ. of
Nevada/Reno (USA)), AK(Univ. of Nevada/Reno (USA)),
AL(Orbital Sciences Corp. (USA)), AM(Computer
Sciences Corp. (USA) and Johns Hopkins Univ. (USA)),
AN(California State Univ./Fullerton (USA))
Publication: Techniques and Instrumentation for Detection of
Exoplanets. Edited by Coulter, Daniel R.
Proceedings of the SPIE, Volume 5170, pp. 262-271
(2003).
Publication Date: 11/2003
Origin: SPIE
Abstract Copyright: (c) 2003: SPIE--The International Society for
Optical Engineering. Downloading of the abstract is
permitted for personal use only.
DOI: 10.1117/12.506192
Bibliographic Code: 2003SPIE.5170..262S
Abstract
In this manuscript, we further develop our concepts for the free-flying
occulter space-based mission, the Umbral Missions Blocking Radiating
Astronomical Sources (UMBRAS). Our optical simulations clearly show that
an UMBRAS-like mission designed around a 4-m telescope and 10-m occulter
could directly image terrestrial planets. Such a mission utilizing
existing technology could be built and flown by the end of the decade.
Moreover, many of the other proposed concepts for Terrestrial Planet
Finder (TPF) could significantly benefit by using an external occulter.
We present simultations for an optical design comprising a square
aperture telescope plus square external occulter. We show that the
entire diffraction pattern, which is propagated from occulter to
telescope and through telescope to focal plane, may be characterized by
two parameters, the Fresnel number and the ratio of the telescope
diameter to the occulter width. Combining the effects of a square
occulter with apodization provides a much more rapid roll-off in the PSF
intensity between the diffraction spikes than may be achieved with an
unapodized telecope aperture and occulter. We parameterize our results
with respect to wavefront quality and compare them against other
competing methods for exo-planet imaging. The combination of external
occulter and apodization yields the required contrast in the region of
the PSF essential for exo-planet detection. An occulter external to the
telescope (i.e., in a separate spacecraft, as opposed to a classical
coronagraph with internal occulter) reduces light scatter within the
telescope by approximately 2 orders of magnitude. This is due to less
light actually entering the telescope. Reduced scattered light
significantly relaxes the constraints on the mirror surface roughness,
especially in the mid-spatial frequencies critical for planet detection.
This study, plus our previous investigations of engineering as well as
spacecraft rendezvous and formation flying clearly indicates that the
UMBRAS concept is very competitive with, or superior to, other proposed
concepts for TPF missions.
Title: Imaging the Surfaces and Interiors of Other Stars:
The Stellar Imager (SI) Mission Concept
Authors: Carpenter, K. G.; Lyon, R. G.; Schrijver, C. J.;
Mundy, L. J.; Allen, R. J.; Rajagopal, J.
Publication: The Future of Cool-Star Astrophysics: 12th Cambridge
Workshop on Cool Stars, Stellar Systems, and the Sun
(2001 July 30 - August 3), eds. A. Brown, G.M.
Harper, and T.R. Ayres, (University of Colorado),
2003, p. 1091-1096.
Publication Date: 10/2003
Origin: AUTHOR
Keywords: Stellar Imager, Interferometers, Stellar Activity,
Magnetic Activity, Future Space Missions
Bibliographic Code: 2003csss...12.1091C
Abstract
The Stellar Imager (SI) is envisioned as a large (0.5 km diameter)
space-based, UV-optical interferometer. It is designed to image surface
features and, through asteroseismology, sub-surface structures of other
stars and measure their spatial and temporal variations. These
observations are needed to improve our understanding of the underlying
dynamo process(es) and enable improved forecasting of solar/stellar
activity and its impact on planetary climates and life. Schrijver and
Carpenter (this volume) discuss the science goals of the mission in
detail, while in this paper we discuss the performance requirements
implied by the science goals and how these translate into specific
design requirements on the mission architecture, and we present some
preliminary visions for how the required observations (e.g., 1000 pixel,
100 micro-arcsec resolution, UV-optical images of the surface of nearby
dwarf stars) for this ambitious project might be obtained.
Title: Future Capabilities for Solar/Stellar Observations
Authors: Carpenter, K.; Hassler, D.; Berger, T.; Bastian, T.;
Pallavicini, R.; Balachandran, S.
Publication: The Future of Cool-Star Astrophysics: 12th Cambridge
Workshop on Cool Stars, Stellar Systems, and the
Sun (2001 July 30 - August 3), eds. A. Brown, G.M.
Harper, and T.R. Ayres, (University of Colorado),
2003, p. 359-582.
Publication Date: 10/2003
Origin: AUTHOR
Bibliographic Code: 2003csss...12..359C
Abstract
This session outlines the potential instrumental capabilities for the
observation of cool stars and the Sun. The individual contributions
cover space-based solar missions (Hassler), ground-based solar
optical/IR instruments (Berger), solar-stellar radio capabilities
(Bastian), space-based stellar missions (Carpenter), ground-based
optical (Pallavicini) and infrared facilities (Balachandran) for stellar
observations.
Title: Radiochemical sterilization and its use for sutures
Authors: Shalaby, S. W.; Doyle, Y.; Anneaux, B. L.;
Carpenter, K. A.; Schiretz, F. R.
Affiliation: AA(Poly-Med, Inc., R & D Laboratories, 511
Westinghouse Road, 29670, Pendleton, SC, USA),
AB(MDS-Nordion, 535 Boulevard Cartier, , Que., H7N
429, Laval, Canada), AC(Poly-Med, Inc., R & D
Laboratories, 511 Westinghouse Road, 29670,
Pendleton, SC, USA), AD(Poly-Med, Inc., R & D
Laboratories, 511 Westinghouse Road, 29670,
Pendleton, SC, USA), AE(Poly-Med, Inc., R & D
Laboratories, 511 Westinghouse Road, 29670,
Pendleton, SC, USA)
Publication: Nuclear Instruments and Methods in Physics Research
Section B, Volume 208, p. 110-114.
Publication Date: 08/2003
Origin: ELSEVIER
Abstract Copyright: (c) 2003 Elsevier B.V.
DOI: 10.1016/S0168-583X(03)00654-2
Bibliographic Code: 2003NIMPB.208..110S
Abstract
Radiochemical sterilization (RC-S) represents a novel approach to
medical device sterilization. It is a hybrid process encompassing the
attributes of chemical and high-energy radiation sterilization without
the drawbacks associated with the use of the parent processes. It
entails the use of a 5-7.5 kGy of gamma radiation and a
polyformaldehyde insert capable of a radiolytic-controlled release of
formaldehyde gas in a hermetically sealed package under dry nitrogen.
The RC-S process has been applied successfully to radiation-sensitive
sutures, namely polypropylene monofilaments and absorbable polyglycolide
braids.
Title: High Mass Triple Systems: The Classical Cepheid Y
Car
Authors: Evans, N. R.; Carpenter, K. C.; Robinson, R.;
Kienzle, F.; Dekas, A.
Affiliation: AA(Harvard-Smithsonian CfA), AB(NASA's GSFC),
AC(Johns Hopkins University), AD(Geneva
Observatory), AE(Harvard College)
Publication: American Astronomical Society Meeting 202, \#39.06;
Bulletin of the American Astronomical Society, Vol.
35, p.755
Publication Date: 05/2003
Origin: AAS
Abstract Copyright: (c) 2003: American Astronomical Society
Bibliographic Code: 2003AAS...202.3906E
Abstract
We have obtained an HST STIS ultraviolet high dispersion Echelle mode
spectrum of the double mode classical Cepheid Y Car. The velocity
measured for the hot companion from this spectrum is very divergent from
reasonable predictions for binary motion, implying that the companion is
itself a short period binary. The measured velocity changed by 7 km
sec-1 during the 4 days between two segments of the
observation confirming this interpretation. We summarize ``binary"
Cepheids which are in fact members of triple systems and find 50% are
triples. This fraction may be overestimated since binary companions
increase the orbital motion of the Cepheids and make them more likely to
be detected and studied.
Financial assistance was provided by HST grant HST-GO-09146.01-A and
from the Chandra X-ray Center NASA Contract NAS8-39073.
Title: Winds from ``Non-Coronal'' and ``Hybrid'' Stars
Driven by MHD Waves
Authors: Airapetian, V. S.; Carpenter, K.; Ofman, L.
Affiliation: AA(The Catholic University of America/GSFC),
AB(NASA/GSFC), AC(The Catholic University of
America/GSFC)
Publication: American Astronomical Society Meeting 202, \#32.14;
Bulletin of the American Astronomical Society, Vol.
35, p.745
Publication Date: 05/2003
Origin: AAS
Abstract Copyright: (c) 2003: American Astronomical Society
Bibliographic Code: 2003AAS...202.3214A
Abstract
Observations obtained with IUE, HST and FUSE provide extensive data on
atmospheric heating and wind dynamics for late-type luminous stars. The
physical processes which drive winds in these stars are poorly
understood, despite decades of study. In our previous study we have
shown that observational signatures of winds can be interpreted by our
model of winds driven by propagated Alfvén waves in stellar
atmospheres and launched at a single frequency at the wind base
(Airapetian et al. 2000). We extend our MHD calculations of winds from
luminous late-type stars to include an Alfvén wave driver with a
broad-band frequency range. The calculations are applied to
``non-coronal'' (alpha Tau) and ``hybrid'' (beta Dra) giant stars to
consistently reproduce the observed velocity profiles of the winds, its
terminal velocity, the turbulent broadening of UV lines and mass loss
rates. The nature of wind variability in luminous late-type stars is
discussed. We also present the preliminary results of our first MHD and
LTE radiative transfer calculations to model the UV spectra from the K5
giant, alpha Tau.
This research is supported by the NASA Research grant from GSFC No.
NAG5-12869.
Title: UMBRAS: a matched occulter and telescope for imaging
extrasolar planets
Authors: Schultz, Alfred B.; Jordan, Ian J.; Kochte, Mark;
Fraquelli, Dorothy A.; Bruhweiler, Fred;
Hollis, Jan M.; Carpenter, Kenneth G.;
Lyon, Richard G.; DiSanti, Mike A.;
Miskey, Cherie L.; Leitner, Jesse; Burns, Richard D.;
Starin, Scott R.; Rodrigue, Melodi; Fadali, M. S.;
Skelton, Dennis L.; Hart, Helen M.;
Hamilton, Forrest C.; Cheng, Kwang-Ping
Affiliation: AA(Computer Sciences Corp. and Space Telescope
Science Institute (USA)), AB(Computer Sciences Corp.
and Space Telescope Science Institute (USA)),
AC(Computer Sciences Corp. and Space Telescope
Science Institute (USA)), AD(Computer Sciences Corp.
and Space Telescope Science Institute (USA)),
AE(Catholic Univ. of America (USA)), AF(NASA Goddard
Space Flight Ctr. (USA)), AG(NASA Goddard Space
Flight Ctr. (USA)), AH(NASA Goddard Space Flight
Ctr. (USA)), AI(Catholic Univ. of America (USA)),
AJ(Catholic Univ. of America (USA)), AK(NASA Goddard
Space Flight Ctr. (USA)), AL(NASA Goddard Space
Flight Ctr. (USA)), AM(NASA Goddard Space Flight
Ctr. (USA)), AN(Univ. of Nevada/Reno (USA)),
AO(Univ. of Nevada/Reno (USA)), AP(Orbital Sciences
Corp. (USA)), AQ(Computer Sciences Corp. and Johns
Hopkins Univ. (USA)), AR(Computer Sciences Corp. and
Space Telescope Science Institute (USA)),
AS(California State Univ./Fullerton (USA))
Publication: High-Contrast Imaging for Exo-Planet Detection.
Edited by Alfred B. Schultz. Proceedings of the
SPIE, Volume 4860, pp. 54-61 (2003).
Publication Date: 02/2003
Origin: SPIE
Abstract Copyright: (c) 2003: SPIE--The International Society for
Optical Engineering. Downloading of the abstract is
permitted for personal use only.
Bibliographic Code: 2003SPIE.4860...54S
Abstract
We describe a 1-meter space telescope plus free-flying occulter craft
mission that would provide direct imaging and spectroscopic observations
of Jovian and Uranus-sized planets about nearby stars not detectable by
Doppler techniques. The Doppler technique is most sensitive for the
detection of massive, close-in extrasolar planets while the use of a
free-flying occulter would make it possible to image and study stellar
systems with planets comparable to our own Solar System. Such a mission
with a larger telescope has the potential to detect earth-like planets.
Previous studies of free-flying occulters reported advantages in having
the occulting spot outside the telescope compared to a classical
coronagraph onboard a space telescope. Using an external occulter means
light scatter within the telescope is reduced due to fewer internal
obstructions and less light entering the telescope and the polishing
tolerances of the primary mirror and the supporting optics can be less
stringent, thereby providing higher contrast and fainter detection
limits. In this concept, the occulting spot is positioned over the star
by translating the occulter craft, at distances of 1,000 to 15,000 kms
from the telescope, on the sky instead of by moving the telescope. Any
source within the telescope field-of-view can be occulted without moving
the telescope. In this paper, we present our current concept for a 1-m
space telescope matched to a free-flying occulter, the Umbral Missions
Blocking Radiating Astronomical Sources (UMBRAS) space mission. An
UMBRAS space mission consists of a Solar Powered Ion Driven Eclipsing
Rover (SPIDER) occulter craft and a matched (apodized) telescope. The
occulter spacecraft would be semi-autonomous, with its own propulsion
systems, internal power (solar cells), communications, and navigation
capability. Spacecraft rendezvous and formation flying would be achieved
with the aid of telescope imaging, RF or laser ranging, celestial
navigation inputs, and formation control algorithms.
Title: Stellar Imager (SI) mission concept
Authors: Carpenter, Kenneth G.; Schrijver, Carolus J.;
Lyon, Richard G.; Mundy, Lee G.; Allen, Ronald J.;
Armstrong, J. Thomas; Danchi, William C.;
Karovska, Margarita; Marzouk, Joseph;
Mazzuca, Lisa M.; Mozurkewich, David; Neff, Susan G.;
Pauls, Thomas A.; Rajagopal, Jayadev K.;
Solyar, Gregory; Zhang, Xiaolei
Affiliation: AA(NASA Goddard Space Flight Ctr. (USA)),
AB(Lockheed Martin Advanced Technology Ctr. (USA)),
AC(NASA Goddard Space Flight Ctr. (USA)), AD(Univ.
of Maryland/College Park (USA)), AE(Space Telescope
Science Institute (USA)), AF(Naval Research Lab.
(USA)), AG(NASA Goddard Space Flight Ctr. (USA)),
AH(Harvard-Smithsonian Ctr. for Astrophysics (USA)),
AI(Sigma Research and Engineering Corp. (USA)),
AJ(NASA Goddard Space Flight Ctr. (USA)), AK(Naval
Research Lab. (USA)), AL(NASA Goddard Space Flight
Ctr. (USA)), AM(Naval Research Lab. (USA)), AN(Space
Telescope Science Institute (USA)), AO(NASA Goddard
Space Flight Ctr. (USA)), AP(Naval Research Lab.
(USA))
Publication: Future EUV/UV and Visible Space Astrophysics
Missions and Instrumentation. Edited by J. Chris
Blades, Oswald H. W. Siegmund. Proceedings of the
SPIE, Volume 4854, pp. 293-302 (2003).
Publication Date: 02/2003
Origin: SPIE
Abstract Copyright: (c) 2003: SPIE--The International Society for
Optical Engineering. Downloading of the abstract is
permitted for personal use only.
DOI: 10.1117/12.459776
Bibliographic Code: 2003SPIE.4854..293C
Abstract
The Stellar Imager (SI) is envisioned as a space-based, UV-optical
interferometer composed of 10 or more one-meter class elements
distributed with a maximum baseline of 0.5 km. It is designed to image
stars and binaries with sufficient resolution to enable long-term
studies of stellar magnetic activity patterns, for comparison with those
on the sun. It will also support asteroseismology (acoustic imaging) to
probe stellar internal structure, differential rotation, and large-scale
circulations. SI will enable us to understand the various effects of the
magnetic fields of stars, the dynamos that generate these fields, and
the internal structure and dynamics of the stars. The ultimate goal of
the mission is to achieve the best-possible forecasting of solar
activity as a driver of climate and space weather on time scales ranging
from months up to decades, and an understanding of the impact of stellar
magnetic activity on life in the Universe. In this paper we describe the
scientific goals of the mission, the performance requirements needed to
address these goals, the "enabling technology" development efforts being
pursued, and the design concepts now under study for the full mission
and a possible pathfinder mission.
Title: A novel process to fabricate mirrors with very long
radius and ultrasmooth surfaces
Authors: Chen, Peter C.; Carpenter, Kenneth G.;
Romeo, Robert C.
Affiliation: AA(NASA Goddard Space Flight Ctr. (USA) and
Composite Mirror Applications, Inc. (USA)), AB(NASA
Goddard Space Flight Ctr. (USA)), AC(Composite
Mirror Applications, Inc. (USA))
Publication: Future EUV/UV and Visible Space Astrophysics
Missions and Instrumentation. Edited by J. Chris
Blades, Oswald H. W. Siegmund. Proceedings of the
SPIE, Volume 4854, pp. 21-28 (2003).
Publication Date: 02/2003
Origin: SPIE
Abstract Copyright: (c) 2003: SPIE--The International Society for
Optical Engineering. Downloading of the abstract is
permitted for personal use only.
DOI: 10.1117/12.459949
Bibliographic Code: 2003SPIE.4854...21C
Abstract
During the course of performing space flight qualification testing of
composite mirrors at NASA GSFC, a serendipitious event was observed
which, in retrospect, should have been obvious. Investigation of this
phenomenon leads to a promising avenue towards the fabrication of large
aperture precision spherical mirrors with very long radius of curvature
(>f/100). Such mirrors are required for future missions such as the
Stellar Imager. We report on the observation and analysis of the event,
optical measurements, and the development of associated active figure
control systems.
Title: Simulating dilute-aperture imaging: The Stellar
Imager
Authors: Rajagopal, Jayadev K.; Böker, Torsten;
Allen, Ronald J.; Carpenter, Kenneth G.
Affiliation: AA(Space Telescope Science Institute (USA)),
AB(Space Telescope Science Institute and NASA
Goddard Space Flight Ctr. (USA)), AC(Space Telescope
Science Institute (USA)), AD(NASA Goddard Space
Flight Ctr. (USA))
Publication: Interferometry in Space. Edited by Shao, Michael.
Proceedings of the SPIE, Volume 4852, pp. 652-656
(2003).
Publication Date: 02/2003
Origin: SPIE
Abstract Copyright: (c) 2003: SPIE--The International Society for
Optical Engineering. Downloading of the abstract is
permitted for personal use only.
DOI: 10.1117/12.460718
Bibliographic Code: 2003SPIE.4852..652R
Abstract
A number of proposed space missions for high resolution imaging at
wavelengths ranging from IR to UV call for ``dilute-aperture''
Fizeau-mode interferometers. We present here details of a software tool
developed for high fidelity simulations of images obtained with such
instruments. We show simulated images from the Stellar Imager, a mission
concept being developed by NASA's GSFC to obtain high-resolution images
of nearby stars in UV-optical wavelengths. Using the simulator, we study
the capability of the proposed SI design to image stellar surfaces. We
use the simulator to explore parameters of image quality such as
resolution and dynamic range, and to evaluate proposed designs and the
feasibility of science goals.
Title: The Stellar Imager (SI): An Ultra-High Angular
Resolution Ultraviolet/Optical Observatory
Authors: Carpenter, K. G.; Lyon, R. G.; Schrijver, C. J.;
Mundy, L.; Allen, R. J.; Rajagopal, J.
Publication: Hubble's Science Legacy: Future Optical/Ultraviolet
Astronomy from Space, ASP Conference Proceedings,
Vol. 291, held 2-5 April 2002 at University of
Chicago, Chicago, Illinois, USA. Edited by Kenneth
R. Sembach, J. Chris Blades, Garth D. Illingworth
and Robert C. Kennicutt, Jr. ISBN: 1-58381-136-2,
2003., p.355
Publication Date: 00/2003
Origin: ADS
Comment: ISBN: 1-58381-136-2
Bibliographic Code: 2003ASPC..291..355C
Abstract
Not Available
Title: The Fizeau Interferometer Testbed
Authors: Zhang, Xiaolei; Carpenter, Kenneth G.;
Lyon, Richard G.; Huet, Hubert; Marzouk, Joe;
Solyar, Gregory
Publication: eprint arXiv:astro-ph/0212439
Publication Date: 12/2002
Origin: ARXIV
Keywords: Astrophysics
Comment: 9 pages, 3 figures, accepted for publication and
presentation at the 2003 IEEE Aerospace Conference,
Big Sky, Montana
Bibliographic Code: 2002astro.ph.12439Z
Abstract
The Fizeau Interferometer Testbed (FIT) is a collaborative effort
between NASA's Goddard Space Flight Center, the Naval Research
Laboratory, Sigma Space Corporation, and the University of Maryland. The
testbed will be used to explore the principles of and the requirements
for the full, as well as the pathfinder, Stellar Imager mission concept.
It has a long term goal of demonstrating closed-loop control of a sparse
array of numerous articulated mirrors to keep optical beams in phase and
optimize interferometric synthesis imaging. In this paper we present the
optical and data acquisition system design of the testbed, and discuss
the wavefront sensing and control algorithms to be used. Currently we
have completed the initial design and hardware procurement for the FIT.
The assembly and testing of the Testbed will be underway at Goddard's
Instrument Development Lab in the coming months.
Title: Cooperative Public Outreach - It can be Accomplished
Authors: Blasch, K. W.; Carpenter, K. D.; Davis, S. L.;
Smith, C. F.; Washburne, J. C.; Woodard, G. C.
Affiliation: AA(U.S. Geological Survey, 520 N. Park Ave., Suite
221, Tucson, AZ 85719 United States; Department of
Hydrology and Water Resources, University of
Arizona, J.W. Harshbarger 122, 1133 E. North Campus
Dr., P.O. Box 210011, Tucson, AZ 85719 United
of Arizona, J.W. Harshbarger 122, 1133 E. North
Campus Dr. P.O. Box 210011, Tucson, AZ 85719 United
States; ), AC(U.S. Department of Agriculture Forest
Service, Santa Catalina Ranger District, 5700 N.
Sabino Canyon Road, Tucson, AZ 85750 ; ), AD(U.S.
Geological Survey, 520 N. Park Ave., Suite 221,
Tucson, AZ 85719 United States; ), AE(SAHRA,
University of Arizona, J.W. Harshbarger 122, 1133 E.
North Campus Dr. P.O. Box 210011, Tucson, AZ 85719
United States; ), AF(SAHRA, University of Arizona,
J.W. Harshbarger 122, 1133 E. North Campus Dr. P.O.
Box 210011, Tucson, AZ 85719 United States; )
Publication: American Geophysical Union, Fall Meeting 2002,
abstract \#ED61B-0030
Publication Date: 12/2002
Origin: AGU
AGU Keywords: 1800 HYDROLOGY, 1860 Runoff and streamflow, 6605
Education
Abstract Copyright: (c) 2002: American Geophysical Union
Bibliographic Code: 2002AGUFMED61B0030B
Abstract
The U.S. Department of Agriculture, Forest Service (Santa Catalina
Ranger District of the Coronado National Forest), the U.S. Geological
Survey (Water Resources Discipline, Arizona District), and the National
Science Foundation sponsored Science and Technology Center
(Sustainability of semi-Arid Hydrology and Riparian Areas) have created
a series of exhibits on the hydrology of Sabino Creek, an ephemeral
stream within the Sonoran Desert (USA) visited by over 1 million people
annually. A clear set of educational objectives established at the
beginning of the process and interagency cooperation resulted in a
cohesive grouping of exhibits while minimizing single agency dominance.
The multimedia exhibits are a collection of visual displays along with a
touch-screen kiosk that has animations and other links that expand along
many avenues to educate people on ephemeral streams, sky islands,
siltation, and ground-water recharge within the Sonoran Desert. In
addition, the exhibit incorporates real-time climate and streamflow
data collected by four science agencies. The real-time data
incorporated into the kiosk and linking web page is used to educate
visitors about the natural environment within Sabino Canyon and inform
them about flash-flooding and fire dangers. Thus, before entering the
canyon, a visitor can view the exhibit and readily determine the air and
water temperature, stream activity, and several other current and
historical environmental variables. In summary, the cooperative efforts
between the agencies resulted in a series of exhibits that are far more
beneficial to the public than if the efforts had been attempted
separately.
Title: Interpreting the Hydrology of a Desert Mountain
Stream to a General Public: Using Multimedia to
Enhance Informal Experiential Education
Authors: Woodard, G. C.; Carpenter, K. D.
Affiliation: AA(University of Arizona, SAHRA Harshbarger Room 318
University of Arizona, Tucson, AZ 85721 United
AB(University of Arizona, SAHRA Harshbarger Room 318
University of Arizona, Tucson, AZ 85721 United
Publication: American Geophysical Union, Fall Meeting 2002,
abstract \#ED61B-0027
Publication Date: 12/2002
Origin: AGU
AGU Keywords: 1818 Evapotranspiration, 1821 Floods, 1833
Hydroclimatology, 1854 Precipitation (3354), 1860
Runoff and streamflow
Abstract Copyright: (c) 2002: American Geophysical Union
Bibliographic Code: 2002AGUFMED61B0027W
Abstract
Sabino Canyon near Tucson, Arizona draws over 1 million visits per year.
The centerpiece of the canyon is Sabino Creek, an ephemeral stream fed
by seasonal snowmelt and monsoon rains. Frequently asked questions by
canyon visitors include: How can a stream flow in the desert
environment? Why are the surrounding mountaintops so much cooler and
wetter? How can the stream flow without recent rain or snowmelt?
Where does the water go? The NSF STC for Sustainability of semi-Arid
Hydrology and Riparian Areas (SAHRA) has partnered with the USGS and the
USDA Forest Service to develop static displays and a touch-screen
electronic kiosk for the Sabino Canyon Visitors Center that explain what
streamflow is, where the waters of Sabino Creek originate, where they
go, what conditions produce flash flooding, and the hydrology of sky
island environments. The kiosk, and an associated Web site, also give
current weather and streamflow conditions at various points in the
canyon, plus typical and extreme conditions for the current date.
Designing displays that attract and inform a diverse mix of visitors
with varying levels of interest, reading levels, and attention spans is
a major challenge. We have integrated static displays featuring light
boxes with a touch-screen kiosk featuring graphics, animation, video,
sound effects, and voice-overs. Optional sub-titles are in five
languages. The goal is to attract visitors to the display and then meet
their various interests and information needs. Hydrology is a foreign
subject to the great majority of people, and opportunities to informally
educate them are relatively scarce. This presentation will show how
current multimedia technology can be combined with proven methods of
informal experiential education to communicate some basic hydrologic
principles.
Title: Steps Toward a Large Space-Based UV/Optical Fizeau
Interferometer: The GSFC Fizeau Interferometer
Testbed (FIT)
Authors: Carpenter, K. G.; Lyon, R. G.; Mazzuca, L. M.;
Solyar, G.; Marzouk, J.; Mundy, L. G.;
Armstrong, J. T.; Zhang, X.
Affiliation: AA(NASA's GSFC), AB(NASA's GSFC), AC(NASA's GSFC),
AD(GEST/UMBC), AE(Sigma Space), AF(UMD), AG(NRL),
AH(NRL)
Publication: American Astronomical Society, 201st AAS Meeting,
\#82.09; Bulletin of the American Astronomical
Society, Vol. 34, p.1240
Publication Date: 12/2002
Origin: AAS
Abstract Copyright: (c) 2002: American Astronomical Society
Bibliographic Code: 2002AAS...201.8209C
Abstract
Goddard Space Flight Center is pursuing the development of space-based,
long-baseline (>0.5km) UV-optical Fizeau imaging interferometers to
enable the next major stride toward very high angular resolution
astronomical observations. This effort includes the development and
operation of the Fizeau Interferometry Testbed (FIT), in collaboration
with the Naval Research Lab/NPOI, Univ. of MD, and Sigma Space
Corporation. The FIT will be used to explore the principles of and
requirements for the Stellar Imager (SI) mission concept
(http://hires.gsfc.nasa.gov/ ~si) and other such Fizeau
Interferometers/Sparse Aperture Telescope missions, leading in the end
to the Planet Imager (PI), which is the ultimate goal of the current
Origins Program. The primary goal of the FIT program is to demonstrate
closed-loop control of mirrors (tip, tilt, piston, translation of array
elements) and the overall system to keep the optical beams in phase and
enable high quality imaging by a many-element (7-30) Fizeau
Interferometric System. The FIT will also be used to assess various
wavefront reconstruction and sensing and image reconstruction algorithms
for utility and accuracy by application to real data generated by the
Testbed. In this paper, we describe the design and goals of the system,
provide a status report on its construction, and note our future plans.
The FIT development is supported by NASA-ROSS/SARA grants to GSFC, UMD,
and NRL and by internal GSFC R&D funds.
Title: The Stellar Imager (SI): An UV-Optical
Interferometer in Space
Authors: Zhang, X.; Carpenter, K.; Schrijver, C.
Affiliation: AA(SSAI / NASA's GSFC), AB(NASA's GSFC), AC(LMATC)
Publication: American Astronomical Society, 200th AAS Meeting,
\#61.02; Bulletin of the American Astronomical
Society, Vol. 34, p.744
Publication Date: 05/2002
Origin: AAS
Abstract Copyright: (c) 2002: American Astronomical Society
Bibliographic Code: 2002AAS...200.6102Z
Abstract
The Stellar Imager (SI) is envisioned as a space-based, UV-optical
interferometer composed of 10 or more one-meter class mirrors
distributed with a maximum baseline of 0.5 km and providing a resolution
of 60 micro-arcseconds at 1550 A. It will image stars and binaries with
one hundred to one thousand resolution elements on their surfaces and
enable long-term studies of stellar magnetic activity patterns and their
evolution with time, for comparison with those on the sun. It will also
sound their interiors through asteroseismology to image internal
structure, differential rotation, and large-scale circulations. SI will
enable us to understand the various effects of magnetic fields of stars,
the dynamos that generate them, and the internal structure and dynamics
of the stars in which they exist. The ultimate goal is to achieve the
best-possible forecasting of solar activity on times scales ranging up
to decades, and an understanding of the impact of stellar magnetic
activity on life in the Universe. With substantial improvements in
normal-incidence mirror coatings for the EUV, the concept could be
extended into that shorter wavelength regime as well. Fitting naturally
within the NASA long-term time line, SI complements defined missions,
and with them will show us entire other solar systems, from the central
star to their orbiting planets.
Title: What Is Happening at Spectral Type F5 in Hyades F
Stars?
Authors: Böhm-Vitense, Erika; Robinson, Richard;
Carpenter, Kenneth; Mena-Werth, Jose
Affiliation: AA(Astronomy Department, University of Washington,
Seattle, WA 98195), AB(Institute for Astrophysics
and Computational Sciences, Department of Physics,
Catholic University of America, Washington, DC
20064), AC(LASP, NASA Goddard Space Flight Center,
Code 681, Greenbelt, MD 20771), AD(University of
Nebraska at Kearney, Physics Department, Kearney, NE
68849-1160)
Publication: The Astrophysical Journal, Volume 569, Issue 2, pp.
941-963.
Publication Date: 04/2002
Origin: UCP
ApJ Keywords: Galaxy: Open Clusters and Associations: Individual:
Name: Hyades, Stars: Chromospheres, Stars: Coronae,
Stars: Rotation
Abstract Copyright: (c) 2002: The American Astronomical Society
DOI: 10.1086/339395
Bibliographic Code: 2002ApJ...569..941B
Abstract
Aiming at a better understanding of the mechanisms heating the
chromospheres, transition regions, and coronae of cool stars, we study
ultraviolet, low-resolution Hubble Space Telescope/Space Telescope
Imaging Spectrograph spectra of Hyades main-sequence F stars. We study
the B-V dependence(s) of the chromospheric and transition layer emission
line fluxes and their dependences on rotational velocities. We find that
the transition layer emission line fluxes and also those of strong
chromospheric lines decrease steeply between B-V=0.42 and 0.45, i.e., at
spectral type F5, for which the rotational velocities also decrease
steeply. The magnitude of the line-flux decrease increases for lines of
ions with increasing degree of ionization. This shows that the line-flux
decrease is not due to a change in the surface filling factor but rather
due to a change of the relative importance of different heating
mechanisms. For early F stars with B-V<0.42 we find for the
transition layer emission lines increasing fluxes for increasing vsini,
indicating magnetohydrodynamic heating. The vsini dependence is
strongest for the high-ionization lines. On the other hand, the low
chromospheric lines show no dependence on vsini, indicating acoustic
shock heating for these layers. This also contributes to the heating of
the transition layers. The Mg II and Ca II lines show decreasing fluxes
for increasing vsini, as long as vsini is less than ~40 km
s-1. The coronal X-ray emission also decreases for increasing
vsini, except for vsini larger than ~100 km s-1. We have at
present no explanation for this behavior. For late F stars the
chromospheric lines show vsini dependences similar to those observed for
early F stars, again indicating acoustic heating for these layers. We
were unable to determine the vsini dependence of the transition layer
lines because of too few single star targets. The decrease of emission
line fluxes at the spectral type F5, with steeply decreasing vsini,
indicates, however, a decreasing contribution of magnetohydrodynamic
heating for the late F stars. The X-ray emission for the late F stars
increases for increasing vsini, indicating magnetohydrodynamic heating
for the coronae of the late F stars, different from the early F stars.
Based on observations with the NASA/ESA Hubble Space Telescope obtained
at the Space Telescope Science Institute, which is operated by the
Association of Universities for Research in Astronomy, Incorporated,
under NASA contract NAS5-26555.
Title: Estimation of Mass-Loss Rates for M Giants from UV
Emission Line Profiles
Authors: Carpenter, K. G.; Robinson, R. D.
Affiliation: AA(LASP/NASA-GSFC), AB(IACS,CUA/CSC/Dept. of
Physics,JHU)
Publication: American Astronomical Society, 199th AAS Meeting,
\#92.05; Bulletin of the American Astronomical
Society, Vol. 33, p.1441
Publication Date: 12/2001
Origin: AAS
Abstract Copyright: (c) 2001: American Astronomical Society
Bibliographic Code: 2001AAS...199.9205C
Abstract
The photon-scattering winds of M giants produce absorption features in
the strong chromospheric emission lines. These provide us with an
opportunity to assess important parameters of the wind, including flow
and turbulent velocities, the optical depth of the wind above the region
of photon creation, and the star's mass-loss rate. We have used the
Lamers et al. (1987) Sobolev with Exact Integration (SEI) radiative
transfer code, along with simple models of the outer atmospheric
structure and wind, to determine the wind characteristics of two M-giant
stars, gamma Cru (M3.4) and mu Gem (M3IIIab). The SEI code has the
advantage of being computationally fast and allows a great number of
possible wind models to be examined. The analysis procedure involves
specifying wind parameters and then using the program to calculate line
profiles for the Mg II (UV1) lines and a range of unblended Fe II lines.
These lines have a wide range of wind opacities and therefore probe
different heights in the atmosphere. The assumed wind properties are
iterated until the predicted profiles match the observations over as
many lines as possible. We present estimates of the wind parameters for
these stars and offer a comparison to wind properties previously-derived
for low-gravity K stars using the same technique.
Title: Free-flying Occulters for Use with Space Telescopes
Authors: Kochte, M.; Schultz, A. B.; Jordan, I.; Hamilton, F.;
Bruhweiler, F.; DiSanti, M. A.; Burns, R. D.;
Carpenter, K.; Hollis, J. M.; Leitner, J.;
Lyon, R. G.; Starin, S.; Fadali, M. S.; Rodrigue, M.;
Skelton, D. L.; Hart, H. M.
Affiliation: AA(CSC/STScI), AB(CSC/STScI), AC(CSC/STScI),
AD(CSC/STScI), AE(CUA), AF(CUA), AG(NASA/GSFC),
AH(NASA/GSFC), AI(NASA/GSFC), AJ(NASA/GSFC),
AK(NASA/GSFC), AL(NASA/GSFC), AM(UNR), AN(UNR),
AO(OSC), AP(CSC/JHU)
Publication: American Astronomical Society, 199th AAS Meeting,
\#45.01; Bulletin of the American Astronomical
Society, Vol. 33, p.1367
Publication Date: 12/2001
Origin: AAS
Abstract Copyright: (c) 2001: American Astronomical Society
Bibliographic Code: 2001AAS...199.4501K
Abstract
We summarize a free-flying occulter proposal that was submitted to NASA
in response to NRA-01-OSS-04. Free-flying occulters in association with
space telescopes have been proposed for nearly four decades to detect
and study extrasolar planets. External occulters reduce the magnitude
differences between a planet and the host star; light scatter within the
telescope is reduced resulting from fewer obstructions and optical
surfaces; and any instrument onboard the telescope, including
spectrometers, can be used to study extrasolar planets. We conclude with
a mission concept for an optimized optical 1-m space telescope with a
small external occulter. Both craft could be launched from a single
launch vehicle and placed in a 1-AU fall-away orbit or at Earth-Sun L2.
Jovian planets around stars within 10 parsecs could be studied, and a
search for sub-Jovian planets around the nearest handful of stars could
be performed. Approximately 80% of the telescope time would be available
for projects not associated with the external occulter such as
gravitational lensing and planetary transit surveys.
Title: Goddard High Resolution Spectrograph Observations of
NGC 4151
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.;
Boggess, A.; Carpenter, K. G.; Ebbets, D. C.;
Hutchings, J. B.; Jura, M.; Leckrone, D. S.;
Linsky, J. L.; Maran, S. P.; Savage, B. D.;
Smith, A. M.; Trafton, L. M.; Walter, F. M.;
Weymann, R. J.; Snow, M.; Ake, T. B.
Affiliation: AA(; GHRS Investigation Definition Team.; Laboratory
for Atmospheric and Space Physics, University of
Colorado at Boulder, and Institute for Astrophysics,
Department of Physics and Astronomy, University of
New Mexico, 800 Yale Boulevard, NE, Albuquerque, NM
Investigation Definition Team.; Laboratory for
Astronomy and Solar Physics, Code 681, NASA Goddard
Space Flight Center, Greenbelt, MD 20771.), AC(;
GHRS Investigation Definition Team.; Center for
Astrophysics and Space Sciences, University of
California, San Diego, 9500 Gilman Drive, La Jolla,
CA 92093-0424.), AD(; GHRS Investigation Definition
Team.; Postal address: 2420 Balsam Drive, Boulder,
CO 80304.), AE(; GHRS Investigation Definition
Team.; Laboratory for Astronomy and Solar Physics,
Code 681, NASA Goddard Space Flight Center,
Greenbelt, MD 20771.), AF(; GHRS Investigation
Definition Team.; Ball Aerospace and Technologies
Corporation, P.O. Box 1062, AR1, Boulder, CO
80306.), AG(; GHRS Investigation Definition Team.;
Dominion Astrophysical Observatory, 5071 West
Saanich Road, Victoria, BC V8X 4M6, Canada.), AH(;
GHRS Investigation Definition Team.; Department of
Physics and Astronomy, UCLA, Los Angeles, CA
90095-1562.), AI(; GHRS Investigation Definition
Team.; Laboratory for Astronomy and Solar Physics,
Code 681, NASA Goddard Space Flight Center,
Greenbelt, MD 20771.), AJ(; GHRS Investigation
Definition Team.; JILA, University of Colorado and
National Institute of Standards and Technology,
Boulder, CO 80309-0440.), AK(; GHRS Investigation
Definition Team.; Space Sciences Directorate, Code
600, NASA Goddard Space Flight Center, Greenbelt, MD
20771.), AL(; GHRS Investigation Definition Team.;
Department of Astronomy, University of Wisconsin at
Madison, 475 North Charter Street, Madison, WI
53706.), AM(; GHRS Investigation Definition Team.;
Laboratory for Astronomy and Solar Physics, Code
681, NASA Goddard Space Flight Center, Greenbelt, MD
20771.), AN(; GHRS Investigation Definition Team.;
McDonald Observatory and Department of Astronomy,
University of Texas, Austin, TX 78712.), AO(; GHRS
Investigation Definition Team.; Department of
Physics and Astronomy, State University of New York
at Stony Brook, Stony Brook, NY 11794-3800.), AP(;
GHRS Investigation Definition Team.; Observatories
of the Carnegie Institution of Washington, 813 Santa
Barbara Street, Pasadena, CA 91101-1292.), AQ(; GHRS
Science Team.; Laboratory for Atmospheric and Space
Physics, Campus Box 392, University of Colorado,
Boulder, CO 80309.), AR(; GHRS Science Team.;
Science Programs, Computer Sciences Corporation,
Goddard Space Flight Center, Greenbelt, MD 20771.
Current address: Department of Physics and
Astronomy, Johns Hopkins University, 3400 North
Charles Street, Baltimore, MD 21218.)
Publication: The Astronomical Journal, Volume 121, Issue 6, pp.
2999-3000.
Publication Date: 06/2001
Origin: UCP
AJ Keywords: Atlases, Galaxies: Individual: NGC Number: NGC 4151,
Galaxies: Seyfert
Abstract Copyright: (c) 2001: The American Astronomical Society
DOI: 10.1086/321070
Bibliographic Code: 2001AJ....121.2999B
Abstract
Goddard High Resolution Spectrograph observations of the nucleus of the
bright, nearby Seyfert galaxy NGC 4151 are presented andbriefly
described.
Title: AB Dor in '94. I. Hubble Space Telescope Goddard
High Resolution Spectrogaph Observations of the
Quiescent Chromosphere of an Active Star
Authors: Brandt, J. C.; Heap, S. R.; Walter, F. M.;
Beaver, E. A.; Boggess, A.; Carpenter, K. G.;
Ebbets, D. C.; Hutchings, J. B.; Jura, M.;
Leckrone, D. S.; Linsky, J. L.; Maran, S. P.;
Savage, B. D.; Smith, A. M.; Trafton, L. M.;
Weymann, R. J.; Norman, D.; Redfield, S.
Affiliation: AA(; GHRS Investigation Definition Team.; Laboratory
for Atmospheric and Space Physics, Campus Box 392,
University of Colorado, Boulder, CO 80309-0392
of Physics and Astronomy, Institute for
Astrophysics, University of New Mexico, 800 Yale
Boulevard, NE, Albuquerque, NM 87131.), AB(; GHRS
Investigation Definition Team.; Laboratory for
Astronomy and Solar Physics, Goddard Space Flight
Center, Code 681, Greenbelt, MD 20771;
Investigation Definition Team.; Department of
Physics and Astronomy, State University of New York
at Stony Brook, Stony Brook, NY 11794-3800
Definition Team.; Center for Astrophysics and Space
Sciences, University of California, San Diego,
C-0111, La Jolla, CA 92093-0111
Definition Team.; 2420 Balsam Drive, Boulder, CO
Investigation Definition Team.; Laboratory for
Astronomy and Solar Physics, Goddard Space Flight
Center, Code 681, Greenbelt, MD 20771;
Investigation Definition Team.; Ball Aerospace and
Technologies Corporation, PO Box 1062, AR1, Boulder,
Investigation Definition Team.; Dominion
Astrophysical Observatory, 5071 West Saanich Road,
Victoria, V8X 4M6 BC, Canada;
Investigation Definition Team.; Department of
Physics and Astronomy, University of California, Los
Angeles, Los Angeles, CA 90095-1562
Investigation Definition Team.; Laboratory for
Astronomy and Solar Physics, Goddard Space Flight
Center, Code 681, Greenbelt, MD 20771;
Investigation Definition Team.; JILA, University of
Colorado and National Institute of Standards and
Technology, Boulder, CO 80309-0440
Investigation Definition Team.; Space Sciences
Directorate, Code 600, Goddard Space Flight Center,
Greenbelt MD 20771;
Investigation Definition Team.; Department of
Astronomy, University of Wisconsin, 475 North
Charter Street, Madison, WI 53706;
Investigation Definition Team.; Laboratory for
Astronomy and Solar Physics, Goddard Space Flight
Center, Code 681, Greenbelt, MD 20771;
Investigation Definition Team.; MacDonald
Observatory and Astronomy Department, University of
Texas, Austin, TX 78712;
Definition Team.; Observatories of the Carnegie
Institution of Washington, 813 Santa Barbara Street,
Department of Physics and Astronomy, State
University of New York at Stony Brook, Stony Brook,
University of Colorado and National Institute of
Standards and Technology, Boulder, CO 80309-0440
Publication: The Astronomical Journal, Volume 121, Issue 4, pp.
2173-2184.
Publication Date: 04/2001
Origin: UCP
AJ Keywords: ISM: Kinematics and Dynamics, Stars: Activity,
Stars: Chromospheres, Stars: Individual:
Constellation Name: AB Doradus
Abstract Copyright: (c) 2001: The American Astronomical Society
DOI: 10.1086/319958
Bibliographic Code: 2001AJ....121.2173B
Abstract
We analyze Hubble Space Telescope/Goddard High Resolution Spectrograph
spectra of AB Doradus, the prototypical, ultrarapidly rotating K dwarf.
We observed chromospheric (Mg II) and transition-region (C II, Si IV, C
IV, and N V) lines periodically throughout the stellar rotation period
and provide a low-dispersion stellar atlas of 78 emission lines. The
quiescent line profiles of the chromospheric and transition-region lines
show narrow cores superposed on very broad wings. The broad wings of the
Mg II k and h lines and of the transition-region lines can be explained
by emission from gas corotating with the star and extending out to near
the Keplerian corotation radius (2.8 stellar radii). While this is not a
unique solution, it is consistent with previous studies of Halpha
emission, which are naturally explained by large corotating prominences.
We find no evidence for rotational modulation of the emission-line
fluxes. The density diagnostics suggest that the transition region is
formed at constant pressure, with an electron density of
2-3×1012 cm-3 at a temperature of
3×104 K. The electron pressure is about 100 times
larger than that for the quiet Sun. The emission-measure distribution
shows a minimum between logT=5 and 5.5. The Mg II line exhibits three
interstellar absorption components along the 15 pc line of sight. We
identify the lowest velocity component with the G Cloud, but the other
components are not identified with any interstellar clouds previously
detected from other lines of sight.
Title: Mg II Emission Lines of Hyades F Stars
Authors: Böhm-Vitense, Erika; Mena-Werth, Jose;
Carpenter, Kenneth G.; Robinson, Richard D.
Affiliation: AA(Astronomy Department, University of Washington,
Box 351 580, Seattle, WA 98195;
Nebraska at Kearney, Physics Department, Kearney, NE
NASA-Goddard Space Flight Center, Code 681,
AD(Institute for Astrophysics and Computational
Sciences, Department of Physics, Catholic University
of America, Washington DC 20064;
Publication: The Astrophysical Journal, Volume 550, Issue 1, pp.
457-469.
Publication Date: 03/2001
Origin: UCP
ApJ Keywords: Stars: Chromospheres, Ultraviolet: Stars
Abstract Copyright: (c) 2001: The American Astronomical Society
DOI: 10.1086/319723
Bibliographic Code: 2001ApJ...550..457B
Abstract
With the Hubble Space Telescope (HST) we have observed Hyades F stars,
using the Space Telescope Imaging Spectrograph (STIS), in order to get
more information about the heating mechanism(s) for the chromospheres
and transition layers and their dependence on rotation and age. In this
paper we study the Mg II lines at 2800 Å. We include earlier
observations with the International Ultraviolet Explorer (IUE)
satellite. The Mg II emission lines become observable for B-V>0.3.
The emission line fluxes increase steeply until B-V~0.40. For single
stars there is a steep decrease in flux between B-V=0.41 and B-V=0.44,
similar to the behavior of the Ca II emission line cores. For larger B-V
the Mg II emission line fluxes again increase, but much more slowly than
for the Ca II lines. Generally, the low point of the emission is reached
between B-V=0.43 and B-V=0.45, i.e., similar to the Ca II emission
cores. For the Hyades F stars there appears to be a difference between
the emissions for single stars and those for binaries. We find that for
Hyades stars with surface line fluxes larger than 106 ergs
cm-2 s-1 the emission line fluxes decrease with
increasing vsini. For smaller fluxes they may increase with increasing
vsini. We have only three stars that perhaps show this. We study the
flux ratios of the Mg II k and h lines at 2795.7 and 2802.5 Å in
order to determine where the lines fall on the curve of growth. For the
earliest F stars studied here the ratio is close to 2, as expected for
optically thin lines. Generally, it seems that the optical depths in the
line centers are less than 10. There remain problems in understanding
the size of the line widths. We discuss the interpretation of the
Wilson-Bappu effect. For the Hyades F stars there is a strong dependence
of the line width on the effective temperature. Based on observations
with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope
Science Institute, which is operated by the Association of Universities
for Research in Astronomy. Incorporated, under NASA contract NAS5-26555.
Title: correction: Warm-coding deficits and aberrant
inflammatory pain in mice lacking P2X3
Authors: Souslova, Veronika; Cesare, Paolo; Ding, Yanning;
Akoplan, Armen N.; Stanfa, Louise; Suzuki, Rie;
Carpenter, Katherine; Nebenius-Oosthuizen, Daniela;
Smith, Andrew J. H.; Kidd, Emma J.; Wood, John N.
Publication: Nature, Volume 409, Issue 6821, pp. 743 (2001).
Publication Date: 02/2001
Origin: NATURE
Abstract Copyright: (c) 2001: Nature
Bibliographic Code: 2001Natur.409..743S
Abstract
Not Available
Title: The Stellar Imager (SI) mission concept
Authors: Carpenter, Kenneth G.; Neff, Susan G.;
Schrijver, Carolus J.; Allen, Ronald J.;
Rajagopal, Jay
Publication: In: From optical to millimetric interferometry:
scientific and technological challenges. Proceedings
of the 36th Liège International Astrophysics
Colloquium, Liège, Belgium, July 2-5, 2001. Edited
by J. Surdej, J. P. Swings, D. Caro, and A. Detal.
Liège, Belgium: Université de Liège, Institut
d'Astrophysique et de Géophysique, 2001, p. 177 -
183
Publication Date: 00/2001
Origin: ARI
ARI Keywords: Space Interferometers
Bibliographic Code: 2001LIACo..36..177C
Abstract
The Stellar Imager (SI) is envisioned as a space-based, UV-optical
interferometer composed of 10 or more one-meter class elements
distributed with a maximum baseline of 0.5 km. It will image stars and
binaries with one hundred to one thousand resolution elements on their
surface and enable long-term studies of stellar magnetic activity
patterns and their evolution with time, for comparison with those on the
sun. It will also sound their interiors through asteroseismology to
image internal structure, differential rotation, and large-scale
circulations. SI will enable us to understand the various effects of
magnetic fields of stars, the dynamos that generate them, and the
internal structure and dynamics of the stars in which they exist. The
ultimate goal is to achieve the best-possible forecasting of solar
activity on times scales ranging up to decades, and an understanding of
the impact of stellar magnetic activity on astrobiology and life in the
Universe. The road to that goal will revolutionize our understanding of
stars and stellar systems, the building blocks of the Universe. Fitting
naturally within the NASA and ESA long-term time lines, SI complements
defined missions, and with them will show us entire other solar systems,
from the central star to their orbiting planets. In this paper we will
describe the scientific goals of the mission, the performance
requirements needed to address those goals, and the design concepts now
under study.
Title: Estimation of Mass-Loss Rates from Emission Line
Profiles in the UV Spectra of Cool Stars (CD-ROM
Directory: contribs/carpente)
Authors: Carpenter, K. G.; Robinson, R. D.; Harper, G. M.
Publication: 11th Cambridge Workshop on Cool Stars, Stellar
Systems and the Sun, ASP Conference Proceedings,
Vol. 223. Edited by Ram{\'{o}}n J. Garc{\'{\i}}a L{\'{o}}pez, Rafael
Rebolo, and Maria Rosa Zapaterio Osorio. San
Francisco: Astronomical Society of the Pacific,
ISBN: 1-58381-055-2, p.1591
Publication Date: 00/2001
Origin: ADS
Comment: ISBN: 1-58381-055-2
Bibliographic Code: 2001ASPC..223.1591C
Abstract
Not Available
Title: Coordinated Optical, Radio and EUV Observations of a
Flare on YZ CMi (CD-ROM Directory:
contribs/robinson)
Authors: Robinson, R. D.; Airapetian, V.; Slee, O. B.;
Mathioudakis, M.; Carpenter, K. G.
Publication: 11th Cambridge Workshop on Cool Stars, Stellar
Systems and the Sun, ASP Conference Proceedings,
Vol. 223. Edited by Ram{\'{o}}n J. Garc{\'{\i}}a L{\'{o}}pez, Rafael
Rebolo, and Maria Rosa Zapaterio Osorio. San
Francisco: Astronomical Society of the Pacific,
ISBN: 1-58381-055-2, p.1151
Publication Date: 00/2001
Origin: ADS
Comment: ISBN: 1-58381-055-2
Bibliographic Code: 2001ASPC..223.1151R
Abstract
Not Available
Title: Far-UV Echelle Spectroscopy of Arcturus with HST
STIS (CD-ROM Directory: contribs/ayres)
Authors: Ayres, T. R.; Brown, A.; Harper, G. M.;
Bennett, P. D.; Linsky, J. L.; Carpenter, K. G.;
Robinson, R. D.
Publication: 11th Cambridge Workshop on Cool Stars, Stellar
Systems and the Sun, ASP Conference Proceedings,
Vol. 223. Edited by Ram{\'{o}}n J. Garc{\'{\i}}a L{\'{o}}pez, Rafael
Rebolo, and Maria Rosa Zapaterio Osorio. San
Francisco: Astronomical Society of the Pacific,
ISBN: 1-58381-055-2, p.1079
Publication Date: 00/2001
Origin: ADS
Comment: ISBN: 1-58381-055-2
Bibliographic Code: 2001ASPC..223.1079A
Abstract
Not Available
Title: AB Dor in '94: I. HST/GHRS Observations of the
Quiescent Chromosphere of an Active Star
Authors: Brandt, J. C.; Heap, S. R.; Walter, F. M.;
Beaver, E. A.; Boggess, A.; Carpenter, K. G.;
Ebbets, D. C.; Hutchings, J. B.; Jura, M.;
Leckrone, D. S.; Linsky, J. L.; Maran, S. P.;
Savage, B. D.; Smith, A. M.; Trafton, L. M.;
Weymann, R. J.; Norman, D.; Redfield, S.
Publication: eprint arXiv:astro-ph/0012487
Publication Date: 12/2000
Origin: ARXIV
Keywords: Astrophysics
Comment: to appear in The Astronomical Journal, April 2001
Bibliographic Code: 2000astro.ph.12487B
Abstract
We analyze HST/GHRS spectra of AB Doradus, the prototypical
ultra-rapidly rotating K dwarf. We observed chromospheric (Mg II) and
transition region (C II, Si IV, C IV, and N V) lines periodically
throughout the stellar rotation period, and provide a low dispersion
stellar atlas of 78 emission lines. The quiescent line profiles of the
chromospheric and transition region lines show narrow cores superposed
on very broad wings. The broad wings of the Mg II k & h lines and of
the transition region lines can be explained by emission from gas
co-rotating with the star and extending out to near the Keplerian
co-rotation radius (2.8 stellar radii). While this is not a unique
solution, it is consistent with previous studies of H-alpha emission
that are naturally explained by large co-rotating prominences. We find
no evidence for rotational modulation of the emission line fluxes. The
density diagnostics suggest that the transition region is formed at
constant pressure, with an electron density 2-3 E12 /cm^3 at a
temperature of 30,000 K. The electron pressure is about 100 times larger
than that for the quiet Sun. The emission measure distribution shows a
minimum between log(T) = 5 and 5.5. The Mg II line exhibits three
interstellar absorption components along the 15 pc line of sight. We
identify the lowest velocity component with the G cloud, but the other
components are not identified with any interstellar clouds previously
detected from other lines of sight.
Title: Ultraviolet Emission Lines in BA and Non-BA Giants
Authors: Böhm-Vitense, Erika; Carpenter, Kenneth G.;
Robinson, Richard D.
Affiliation: AA(Astronomy Department, University of Washington,
Seattle, WA 98195), AB(LASP, Code 681, NASA Goddard
Space Flight Center, Greenbelt, MD 20771),
AC(Institute for Astrophysics and Computational
Sciences, Department of Physics, Catholic University
of America, Washington, DC 20064)
Publication: The Astrophysical Journal, Volume 545, Issue 2, pp.
992-999.
Publication Date: 12/2000
Origin: UCP
ApJ Keywords: Stars: Chemically Peculiar, Stars: Chromospheres
Abstract Copyright: (c) 2000: The American Astronomical Society
DOI: 10.1086/317850
Bibliographic Code: 2000ApJ...545..992B
Abstract
With the Hubble Space Telescope (HST) and the Goddard High Resolution
Spectrograph we have observed four barium and three weak barium stars in
the ultraviolet spectral region, together with two nonpeculiar giant
standard stars. An additional suspected Ba star was observed with HST
and the Space Telescope Imaging Spectrograph. In the H-R diagram, three
of the observed Ba stars lie on the same evolutionary tracks as the
Hyades giants. Using International Ultraviolet Explorer (IUE) spectra of
previously studied giants together with our HST spectra, we investigate
whether the chromospheric and transition layer emission-line spectra of
the Ba stars are different from those of nonpeculiar giants and from
those of giants with peculiar carbon and/or nitrogen abundances. Except
for the Ba star HD 46407 and the suspected Ba star HD 65699, the Ba star
and mild Ba star emission-line fluxes are, for a given effective
temperature and for a given luminosity, lower than those for the
nonpeculiar giants observed with IUE. In comparison with the
HST-observed standard stars, the C IV lambda1550-to-C II lambda1335
line flux ratios are smaller, but not necessarily so in comparison with
all IUE-observed nonpeculiar giants. However, the C IV-to-C II line flux
ratios for the Ba stars decrease with increasing carbon abundances. This
shows that the energy balance in the lower transition layer is
influenced by the carbon abundance. The temperature gradient appears to
be smaller in the C II line-emitting region. There does not seem to be a
difference in chromospheric electron densities for the Ba and non-Ba
stars, though this result is rather uncertain. Based on observations
with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope
Science Institute, which is operated by the Association of Universities
for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
Title: The Stellar Imager (SI) Mission Concept
Authors: Carpenter, K. G.; Schrijver, C. J.
Affiliation: AA(LASP-NASA/GSFC), AB(Stanford-Lockheed Institute
for Space Research)
Publication: American Astronomical Society, 197th AAS Meeting,
\#14.10; Bulletin of the American Astronomical
Society, Vol. 32, p.1426
Publication Date: 12/2000
Origin: AAS
Abstract Copyright: (c) 2000: American Astronomical Society
Bibliographic Code: 2000AAS...197.1410C
Abstract
The Stellar Imager (SI) is envisioned as a space-based, UV-optical
interferometer composed of 10 or more one-meter class elements
distributed with a maximum baseline of 0.5 km. It will image stars and
binaries with one hundred to one thousand resolution elements on their
surface and enable long-term studies of stellar magnetic activity
patterns and their evolution with time, for comparison with those on the
sun. It will also sound their interiors through asteroseismology to
image internal structure, differential rotation, and large-scale
circulations. SI will enable us to understand the various effects of
magnetic fields of stars, the dynamos that generate them, and the
internal structure and dynamics of the stars in which they exist. The
ultimate goal is to achieve the best-possible forecasting of solar
activity on times scales ranging up to decades, and an understanding of
the impact of stellar magnetic activity on astrobiology and life in the
Universe. The road to that goal will revolutionize our understanding of
stars and stellar systems, the building blocks of the Universe. Fitting
naturally within the NASA long-term time line, SI complements defined
missions, and with them will show us entire other solar systems, from
the central star to their orbiting planets.
Title: Warm-coding deficits and aberrant inflammatory pain
in mice lacking P2X 3 receptors
Authors: Souslova, Veronika; Cesare, Paolo; Ding, Yanning;
Akopian, Armen N.; Stanfa, Louise; Suzuki, Rie;
Carpenter, Katherine; Dickenson, Anthony;
Boyce, Susan; Hill, Ray;
Nebenius-Oosthuizen, Daniela; Smith, Andrew J. H.;
Kidd, Emma J.; Wood, John N.
Affiliation: AA(Department of Biology and), AB(Department of
Biology and), AC(Department of Biology and),
AD(Department of Biology and), AE(Department of
Pharmacology, University College London, London WC1E
6BT, UK), AF(Department of Pharmacology, University
College London, London WC1E 6BT, UK), AG(Department
of Pharmacology, University College London, London
WC1E 6BT, UK), AH(Department of Pharmacology,
University College London, London WC1E 6BT, UK),
AI(Merck Sharp and Dohme Research Labs, Terlings
Park, Essex CM20 2QR, UK), AJ(Merck Sharp and Dohme
Research Labs, Terlings Park, Essex CM20 2QR, UK),
AK(Centre for Genome Research, Edinburgh University,
Edinburgh EH9 3JQ, UK), AL(Centre for Genome
Research, Edinburgh University, Edinburgh EH9 3JQ,
UK), AM(Welsh School of Pharmacy, Cardiff
University, Cardiff CF1 3XF, UK), AN(Department of
Biology and)
Publication: Nature, Volume 407, Issue 6807, pp. 1015-1017
(2000).
Publication Date: 10/2000
Origin: NATURE
Abstract Copyright: (c) 2000: Nature
Bibliographic Code: 2000Natur.407.1015S
Abstract
ATP activates damage-sensing neurons (nociceptors) and can evoke a
sensation of pain. The ATP receptor P2X3 is selectively
expressed by nociceptors and is one of seven ATP-gated, cation-selective
ion channels. Here we demonstrate that ablation of the P2X3
gene results in the loss of rapidly desensitizing ATP-gated cation
currents in dorsal root ganglion neurons, and that the responses of
nodose ganglion neurons to ATP show altered kinetics and pharmacology
resulting from the loss of expression of P2X2/3
heteromultimers. Null mutants have normal sensorimotor function.
Behavioural responses to noxious mechanical and thermal stimuli are also
normal, although formalin-induced pain behaviour is reduced. In
contrast, deletion of the P2X3 receptor causes enhanced
thermal hyperalgesia in chronic inflammation. Notably, although
dorsal-horn neuronal responses to mechanical and noxious heat
application are normal, P2X3-null mice are unable to code the
intensity of non-noxious `warming' stimuli.
Title: A dream of a mission: the Stellar Imager and Seismic
Probe
Authors: Schrijver, C. J.; Carpenter, K. G.
Affiliation: AA(Stanford-Lockheed Institute for Space Research),
AB(Goddard Space Flight Center)
Publication: American Astronomical Society, SPD Meeting \#31,
\#02.98; Bulletin of the American Astronomical
Society, Vol. 32, p.828
Publication Date: 05/2000
Origin: AAS
Abstract Copyright: (c) 2000: American Astronomical Society
Bibliographic Code: 2000SPD....31.0298S
Abstract
The Stellar Imager and Seismic Probe (SISP) is a mission to understand
the various effects of magnetic fields of stars, the dynamos that
generate them, and the internal structure and dynamics of the stars in
which they exist. The ultimate goal is to achieve the best-possible
forecasting of solar activity on times scales ranging up to decades, and
an understanding of the impact of stellar magnetic activity on
astrobiology and life in the Universe. The road to that goal will
revolutionize our understanding of stars and stellar systems, the
building blocks of the Universe. SISP represents an advance in image
detail of several hundred times over the Hubble Space Telescope. SISP
will zoom in on what today - with few exceptions - we only know as point
sources, revealing processes never before seen, thus providing a tool to
astrophysics as fundamental as the microscope is to the study of life on
Earth. SISP is an ultraviolet aperture-synthesis imager with 8-10
telescopes with meter-class apertures, and a central hub with
focal-plane instrumentation that allows spectrophotometry in passbands
as narrow as a few Angstroms up to hundreds of Angstroms. SISP will
image stars and binaries with one hundred to one thousand resolution
elements on their surface, and sound their interiors through
asteroseismology to image internal structure, differential rotation, and
large-scale circulations; this will provide accurate knowledge of
stellar structure and evolution and complex transport processes, and
will impact numerous branches of (astro)physics ranging from the Big
Bang to the future of the Universe. Fitting naturally within the NASA
long-term time line, SISP complements defined missions, and with them
will show us entire other solar systems, from the central star to their
orbiting planets.
Title: A dream of a mission: the stellar imager and seismic
probe.
Authors: Schrijver, C. J.; Carpenter, K. G.
Publication: Bull. Am. Astron. Soc., Vol. 32, No. 2, p. 828,
\#2.98
Publication Date: 05/2000
Origin: ARI
ARI Keywords: Space Missions
Bibliographic Code: 2000BAAS...32R.828S
Abstract
Not Available
Title: A Dream of a Mission: Stellar Imager and Seismic
Probe
Authors: Carpenter, K. G.; Schrijver, C. J.
Affiliation: AA(LASP-NASA/GSFC), AB(SLISR)
Publication: American Astronomical Society, 196th AAS Meeting,
\#32.07; Bulletin of the American Astronomical
Society, Vol. 32, p.721
Publication Date: 05/2000
Origin: AAS
Abstract Copyright: (c) 2000: American Astronomical Society
Bibliographic Code: 2000AAS...196.3207C
Abstract
The Stellar Imager and Seismic Probe (SISP) is a mission to understand
the various effects of magnetic fields of stars, the dynamos that
generate them, and the internal structure and dynamics of the stars in
which they exist. The ultimate goal is to achieve the best-possible
forecasting of solar activity on times scales ranging up to decades, and
an understanding of the impact of stellar magnetic activity on
astrobiology and life in the Universe. The road to that goal will
revolutionize our understanding of stars and stellar systems, the
building blocks of the Universe. SISP will zoom in on what today - with
few exceptions - we only know as point sources, revealing processes
never before seen, thus providing a tool to astrophysics as fundamental
as the microscope is to the study of life on Earth. SISP is an
ultraviolet aperture-synthesis imager with 8-10 telescopes with
meter-class apertures, and a central hub with focal-plane
instrumentation that allows spectrophotometry in passbands as narrow as
a few Angstroms up to hundreds of Angstroms. SISP
will image stars and binaries with one hundred to one thousand
resolution elements on their surface, and sound their interiors through
asteroseismology to image internal structure, differential rotation, and
large-scale circulations; this will provide accurate knowledge of
stellar structure and evolution and complex transport processes, and
will impact numerous branches of (astro)physics ranging from the Big
Bang to the future of the Universe. Fitting naturally within the NASA
long-term time line, SISP complements defined missions, and with them
will show us entire other solar systems, from the central star to their
orbiting planets.
Title: Do All BA II Stars Have White Dwarf Companions?
Authors: Böhm-Vitense, Erika; Carpenter, Kenneth;
Robinson, Richard; Ake, Tom; Brown, Jeffery
Affiliation: AA(Astronomy Department, University of Washington,
Seattle, WA 98195), AB(LASP-NASA/Code 681/Goddard
Space Flight Center, Greenbelt, MD 20771),
AC(Institute for Astrophysics and Computational
Sciences, Department of Physics, Catholic University
of America, Washington, DC 20064), AD(Astronomy
Programs, Computer Sciences Corporation, MD 20715),
AE(Washington State University, Pullman, WA 99164)
Publication: The Astrophysical Journal, Volume 533, Issue 2, pp.
969-983.
Publication Date: 04/2000
Origin: UCP
ApJ Keywords: STARS: BINARIES: GENERAL, STARS: PECULIAR,
ULTRAVIOLET: STARS, STARS: WHITE DWARFS
Abstract Copyright: (c) 2000: The American Astronomical Society
DOI: 10.1086/308678
Bibliographic Code: 2000ApJ...533..969B
Abstract
With the Hubble Space Telescope (HST) and the Goddard High Resolution
Spectrograph (GHRS) we have observed four barium stars, three mild
barium stars, and one weak G-band star in the ultraviolet spectral
region. One barium star was observed with HST and the Space Telescope
Imaging Spectrograph (STIS). The aim was to check the hypothesis that
all these peculiar stars have white dwarf (WD) companions, which at
their asymptotic giant branch phase transferred mass with peculiar
element abundances to the present barium and CH peculiar stars. Assuming
that the ultraviolet continua of the cool giants, including the barium
stars, are generated in their chromospheres and that the relations
between the continua and the emission lines created in the chromospheres
and transition layers are similar in field giants and barium stars, we
found that, indeed, most of our target barium and weak barium stars
appear to have excess flux in the UV when compared to standard giant
stars. For most of the stars the excess flux can be attributed to WD
companions with temperatures between 10,000 and 12,000 K, if the WD mass
is about 0.6 Msolar. Cooling times for the WDs were derived
from their effective temperatures and model calculations by M. Wood. The
calculated cooling times are longer than the lifetimes of the barium
stars on the giant branch. For our target stars the mass transfer
therefore happened while they were still on the main sequence. For two
of the mild barium stars and one or perhaps two barium stars the derived
cooling times for the WD companions come out to be longer than the total
evolutionary times of the barium stars as calculated by Schaller et al.
If our derivations are correct (the error bars are rather large) then
either evolutionary models with larger convective overshoot have to be
used for the barium stars or the cooling times of the white dwarfs have
to be revised downward. Possibly an additional (as yet unknown) cooling
mechanism has to be considered? The weak G-band star HD 165634, which
has a carbon underabundance of about a factor of 10, also appears to
have a WD companion. We discuss the implications of this very low carbon
abundance. Based on observations with the NASA/ESA Hubble Space
Telescope obtained at the Space Telescope Science Institute, which is
operated by the Association of Universities for Research in Astronomy.
Incorporated, under NASA contract NAS5-26555.
Title: Winds from Luminous Late-Type Stars. I. The Effects
of Nonlinear Alfvén Waves
Authors: Airapetian, V. S.; Ofman, L.; Robinson, R. D.;
Carpenter, K.; Davila, J.
Affiliation: AA(Computer Sciences Corporation, Science Programs,
NASA/GSFC, Greenbelt, MD 20771), AB(Raytheon ITSS,
Code 682, NASA/GSFC, Greenbelt, MD 20771),
AC(Catholic University of America, Physics
Department, Washington, DC 20015), AD(LASP,
NASA/GSFC, Greenbelt, MD 20771), AE(LASP, NASA/GSFC,
Greenbelt, MD 20771)
Publication: The Astrophysical Journal, Volume 528, Issue 2, pp.
965-971.
Publication Date: 01/2000
Origin: UCP
ApJ Keywords: MAGNETOHYDRODYNAMICS: MHD, STARS: INDIVIDUAL:
CONSTELLATION NAME: &ALPHA; ORIONIS, STARS: WINDS,
OUTFLOWS, STARS: SUPERGIANTS, WAVES
Abstract Copyright: (c) 2000: The American Astronomical Society
DOI: 10.1086/308198
Bibliographic Code: 2000ApJ...528..965A
Abstract
We present the results of magnetohydrodynamic (MHD) modeling of winds
from luminous late-type stars using a 2.5-dimensional, nonlinear MHD
computer code. We assume that the wind is generated within an initially
hydrostatic atmosphere and is driven by torsional Alfvén waves
generated at the stellar surface. Two cases of atmospheric topology are
considered: case I has longitudinally uniform density distribution and
isotropic radial magnetic field over the stellar surface, and case II
has an isotropic, radial magnetic field with a transverse density
gradient, which we refer to as an ``atmospheric hole.'' We use the same
set of boundary conditions for both models.The calculations are designed
to model a cool luminous star, for which we assume an initial
hydrostatic pressure scale height of 0.072 R*, an
Alfvén wave speed of 92 km s-1 at the surface, and a
wave period of 76 days, which roughly corresponds with the convective
turnover time. For case I the calculations produce a wind with terminal
velocity of ~22 km s-1 and a mass loss rate comparable to the
expected value of 10-6 Msolar yr-1. For
case II we predict a two-component wind: a fast (25 km s-1)
and relatively dense wind outside of the atmospheric hole and a slow (15
km s-1), rarefied wind inside of the hole.
Title: Critical Complements: Progress on the Orbit of T Mon
Authors: Evans, N. R.; Carpenter, K.; Robinson, R.; Massa, D.;
Wahlgren, G. M.; Vinkó, J.; Szabados, L.
Publication: The Impact of Large-Scale Surveys on Pulsating Star
Research, ASP Conference Series, Vol. 203; also IAU
Colloquium \#176. Edited by L. Szabados and D.
Kurtz. ISBN: 1-58381-030-7 (2000), p.246-247
Publication Date: 00/2000
Origin: AUTHOR
Comment: ISBN: 1-58381-030-7
Bibliographic Code: 2000ASPC..203..246E
Abstract
A preliminary orbit has been derived for the high luminosity, 27-d
classical Cepheid T Mon. Velocities for the hot companion have been
measured from an HST GHRS spectrum and 3 IUE spectra. The companion
velocities are inconsistent with binary orbital motion and it is likely
that the companion is itself a short period binary. The HST spectrum
also shows that the companion is a chemically peculiar star, probably
magnetic.
Title: Toward an Orbit for the High-Luminosity Cepheid T
Monocerotis
Authors: Evans, Nancy Remage; Carpenter, Kenneth;
Robinson, Richard; Massa, Derck; Wahlgren, Glenn M.;
Vinko, Jozsef; Szabados, Laszlo
Publication: The Astrophysical Journal, Volume 524, Issue 1, pp.
379-393.
Publication Date: 10/1999
Origin: UCP
ApJ Keywords: STARS: BINARIES: SPECTROSCOPIC, STARS: VARIABLES:
CEPHEIDS, STARS: CHEMICALLY PECULIAR, STARS:
FUNDAMENTAL PARAMETERS, STARS: INDIVIDUAL (T
MONOCEROTIS), ULTRAVIOLET: STARS
Abstract Copyright: (c) 1999: The American Astronomical Society
DOI: 10.1086/307810
Bibliographic Code: 1999ApJ...524..379E
Abstract
We have obtained new velocities of the long-period Cepheid T Mon from
the ground and velocities of its hot companion with the Hubble Space
Telescope (HST) and the International Ultraviolet Explorer (IUE).
Although observations do not cover a full orbit, both the maximum and
minimum orbital velocities have now been obtained. We present a
preliminary orbit and discuss the uncertainties in the orbital
parameters. The velocities for the companion appear to be inconsistent
with binary orbital motion, and it is likely that the companion is
itself a binary in a short-period orbit. The HST spectrum of the
companion shows that it is a chemically peculiar star, probably
magnetic. Because it is coupled with the more massive Cepheid, it must
be very close to the zero-age main sequence. The well-determined mass
function from the preliminary orbit implies that the inclination of the
long-period system is close to 90 deg.
Title: GHRS Observations of Cool, Low-Gravity Stars. V. The
Outer Atmosphere and Wind of the Nearby K Supergiant
lambda Velorum
Authors: Carpenter, Kenneth G.; Robinson, Richard D.;
Harper, Graham M.; Bennett, Philip D.;
Brown, Alexander; Mullan, Dermott J.
Publication: The Astrophysical Journal, Volume 521, Issue 1, pp.
382-406.
Publication Date: 08/1999
Origin: APJ
ApJ Keywords: STARS: ATMOSPHERES, STARS: CHROMOSPHERES, STARS:
INDIVIDUAL (LAMBDA VELORUM), STARS: LATE-TYPE,
STARS: MASS LOSS, STARS: SUPERGIANTS
Abstract Copyright: (c) 1999: The American Astronomical Society
DOI: 10.1086/307520
Bibliographic Code: 1999ApJ...521..382C
Abstract
UV spectra of lambda Velorum taken with the Goddard High Resolution
Spectrograph (GHRS) on the Hubble Space Telescope are used to probe the
structure of the outer atmospheric layers and wind and to estimate the
mass-loss rate from this K5 Ib-II supergiant. VLA radio observations at
lambda=3.6 cm are used to obtain an independent check on the wind
velocity and mass-loss rate inferred from the UV observations.
Parameters of the chromospheric structure are estimated from
measurements of UV line widths, positions, and fluxes and from the UV
continuum flux distribution. The ratios of optically thin C II] emission
lines indicate a mean chromospheric electron density of logN_e~8.9+/-0.2
cm^-3. The profiles of these lines indicate a chromospheric turbulence
(v_0~25-36 km s^-1), which greatly exceeds that seen in either the
photosphere or wind. The centroids of optically thin emission lines of
Fe II and of the emission wings of self-reversed Fe II lines indicate
that they are formed in plasma approximately at rest with respect to the
photosphere of the star. This suggests that the acceleration of the wind
occurs above the chromospheric regions in which these emission line
photons are created. The UV continuum detected by the GHRS clearly
traces the mean flux-formation temperature as it increases with height
in the chromosphere from a well-defined temperature minimum of 3200 K up
to about 4600 K. Emission seen in lines of C III] and Si III] provides
evidence of material at higher than chromospheric temperatures in the
outer atmosphere of this noncoronal star. The photon-scattering wind
produces self-reversals in the strong chromospheric emission lines,
which allow us to probe the velocity field of the wind. The velocities
to which these self-absorptions extend increase with intrinsic line
strength, and thus height in the wind, and therefore directly map the
wind acceleration. The width and shape of these self-absorptions reflect
a wind turbulence of ~9-21 km s^-1. We further characterize the wind by
comparing the observations with synthetic profiles generated with the
Lamers et al. Sobolev with Exact Integration (SEI) radiative transfer
code, assuming simple models of the outer atmospheric structure. These
comparisons indicate that the wind in 1994 can be described by a model
with a wind acceleration parameter beta~0.9, a terminal velocity of
29-33 km s^-1, and a mass-loss rate~3x10^-9 M_solar yr^-1. Modeling of
the 3.6 cm radio flux observed in 1997 suggests a more slowly
accelerating wind (higher beta) and/or a higher mass-loss rate than
inferred from the UV line profiles. These differences may be due to
temporal variations in the wind or from limitations in one or both of
the models. The discrepancy is currently under investigation.
Title: A Search for Microflaring Activity on DME Flare
Stars. II. Observations of YZ Canis Minoris
Authors: Robinson, R. D.; Carpenter, K. G.; Percival, J. W.
Publication: The Astrophysical Journal, Volume 516, Issue 2, pp.
916-923.
Publication Date: 05/1999
Origin: APJ
ApJ Keywords: STARS: ACTIVITY, STARS: FLARE, STARS: INDIVIDUAL (YZ
CANIS MINORIS, CN LEONIS), ULTRAVIOLET: STARS
Abstract Copyright: (c) 1999: The American Astronomical Society
DOI: 10.1086/307133
Bibliographic Code: 1999ApJ...516..916R
Abstract
We report on time-series photometric observations of the dM4.5e flare
star YZ Canis Minoris obtained in 1993 November with the High Speed
Photometer on board the Hubble Space Telescope. The data consist of five
30 minute time sequences with a sampling rate of 0.01 s that were taken
through the F240W filter (centered at 240 nm with an 80 nm width). At
these wavelengths the stellar photospheric background is small, so
relatively small flares can be detected. The observations show a stellar
background of 120 counts s^-1 on which are superposed 54 flare events
ranging in integrated flux from 2.0x10^28 to 3.0x10^30 ergs, as well as
longer term variations with an amplitude of up to 50% of the average
continuum intensity and timescales ranging from several minutes to
hours. A statistical analysis of this background suggests that it may be
composed of unresolved microflaring activity that has an energy
distribution considerably steeper than that deduced for the larger flare
events. This is consistent with previous observations as well as the
self-organized criticality and reconnecting current sheet flare
theories. These results are compared with data from the dM8e flare star
CN Leonis, which was obtained earlier with the same experimental setup.
CN Leo has both a smaller stellar background and a lower flare
occurrence rate than YZ CMi. The fact that CN Leo also has a quiescent
X-ray flux that is less than 10% of the YZ CMi emission suggests a link
between chromospheric and coronal heating.
Title: STIS UV Atlas of the Red Giant Arcturus(1)
Authors: Ayres, T. R.; Brown, A.; Harper, G. M.;
Bennett, P. D.; Linsky, J. L.; Carpenter, K. G.;
Robinson, R. D.
Affiliation: AA(CASA), AB(CASA), AC(CASA), AD(CASA), AE(JILA),
AF(GSFC), AG(CSC)
Publication: American Astronomical Society, 194th AAS Meeting,
\#67.01; Bulletin of the American Astronomical
Society, Vol. 31, p.930
Publication Date: 05/1999
Origin: AAS
Abstract Copyright: (c) 1999: American Astronomical Society
Bibliographic Code: 1999AAS...194.6701A
Abstract
The Space Telescope Imaging Spectrograph (STIS) conducted a series of
observations of the archetype ``noncoronal'' red giant Arcturus (HD
124897; alpha Boo; K1 III) on 24 August 1998, 17--23 UT. The STIS
program was the result of a failed cycle 5 pointing, which could not be
rescheduled during the abbreviated cycle 6, and was carried over to
cycle 7. Three grating settings---E230H (t_exp= 1340 s), E230M (2493 s),
and E140M (5208 s)---covered the ultraviolet spectrum from 1150--2850
Angstroms, at resolutions between R ~ 4*E(4) - 1*E(5) , with essentially
no gaps. The resulting spectrograms are stunning. The resolution is very
high, as is the S/N; the spectral coverage is broad and comprehensive.
The far-UV interval (1150--1700 Angstroms) is a rich emission line
spectrum, dominated by the broad resonance transitions of atomic
hydrogen (lambda 1215) and oxygen (lambda 1305 triplet). There are
numerous narrow emissions, mostly from low-excitation species such as Si
I, Fe II, and fluoresced bands of carbon monoxide. Surprisingly,
high-excitation species---Si IV (lambda 1393: 6*E(4) K) and C IV (lambda
1548: 1*E(5) K)---are present as well (as seen in the earlier ``failed''
GHRS spectra). The mid-UV (1700--2600 Angstroms) shows additional
emission lines, particularly [C II] and [Si II] in the 2325 Angstroms
region; the photospheric continuum rises strongly toward the longer
wavelengths. The 2600--2850 Angstroms interval is mostly a photospheric
absorption spectrum, although the bright chromospheric emission doublet
of Mg II lords over the 2800 Angstroms region. We present a
comprehensive spectral atlas based on our reductions of the STIS
echellograms. We discuss the processing strategies, line
identifications, and some of the preliminary results from our analysis
of this windy, noncoronal giant. (1) This work was supported by grants
GO-06066.01-94A from STScI, and NAG5-3226 from NASA. Observations were
from the NASA/ESA HST, collected at the STScI, operated by AURA, under
contract NAS5-26555.
Title: Lines of OIV and SIV in the Goddard High-Resolution
Spectrograph spectrum of RR Tel: constraints on
atomic data
Authors: Harper, G. M.; Jordan, C.; Judge, P. G.;
Robinson, R. D.; Carpenter, K. G.; Brage, T.
Affiliation: AA(Center for Astrophysics and Space Astronomy,
University of Colorado, Boulder, CO 80309-0389, USA
), AB(Department of Physics (Theoretical Physics),
University of Oxford, 1 Keble Road, Oxford OX1 3NP
), AC(High Altitude Observatory, National Center for
Atmospheric Research, PO Box 3000, Boulder, CO
80307-3000, USA ), AD(Institute for Astrophysics and
Computational Sciences, Catholic University of
America, Washington, DC 20064, USA ), AE(Laboratory
for Astronomy and Solar Physics, Code 681 NASA-GSFC,
Greenbelt, MD 20771, USA ), AF(Department of
Physics, Lund University, Box 118, 22100 Lund,
Sweden )
Publication: Monthly Notices of the Royal Astronomical Society,
Volume 303, Issue 3, pp. L41-L46.
Publication Date: 03/1999
Origin: MNRAS
MNRAS Keywords: ATOMIC DATA, BINARIES: SYMBIOTIC, STARS: INDIVIDUAL:
RR TEL, ULTRAVIOLET: STARS
Abstract Copyright: (c) 1999 The Royal Astronomical Society
DOI: 10.1046/j.1365-8711.1999.02392.x
Bibliographic Code: 1999MNRAS.303L..41H
Abstract
High signal-to-noise ratio spectra of RR Tel obtained at medium
resolution with the Goddard High-Resolution Spectrograph (GHRS) on the
Hubble Space Telescope (HST) are used to test available atomic data for
the OIV 2s^22p ^2P-2s2p^2 ^4P multiplet (UV 0.01). The fine-structure
intervals of the 2s2p^2 ^4P term given by Moore (1983) appear to need
revision. The flux ratios of lines within multiplet UV (0.01), which
have a common upper level, depend only on transition probabilities. The
observed flux ratio of lines from the ^4P_3/2 level differs from that
predicted by theory, but this difference cannot be attributed to a blend
with a line of SIV]. At the electron densities in the RR Tel nebula,
other flux ratios give information on the relative electron excitation
rates between the ^2P and ^4P fine-structure levels. Using the collision
strengths calculated by Zhang, Graziani & Pradhan, the rate to the
^4P_5/2 level, relative to the rates to the other J states, appears to
be underestimated by ~ 10 per cent, which is within the expected
uncertainty of 20 per cent. We also discuss the SIV 3s^23p ^2P-3s3p^2
^4P multiplet.
Title: A Goddard High Resolution Spectrograph Atlas of
Echelle Observations of the HGMN Star chi LUPI
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.;
Boggess, A.; Carpenter, K. G.; Ebbets, D. C.;
Hutchings, J. B.; Jura, M.; Leckrone, D. S.;
Linsky, J. L.; Maran, S. P.; Savage, B. D.;
Smith, A. M.; Trafton, L. M.; Walter, F. M.;
Weymann, R. J.; Proffitt, C. R.; Wahlgren, G. M.;
Johansson, S. G.; Nilsson, H.; Brage, T.; Snow, M.;
Ake, T. B.
Publication: The Astronomical Journal, Volume 117, Issue 3, pp.
1505-1548.
Publication Date: 03/1999
Origin: AJ
AJ Keywords: ATLASES, STARS: CHEMICALLY PECULIAR, STARS:
INDIVIDUAL: CONSTELLATION NAME: CHI LUPI
Abstract Copyright: (c) 1999: The American Astronomical Society
DOI: 10.1086/300753
Bibliographic Code: 1999AJ....117.1505B
Abstract
Observations of the ultra-sharp-lined, chemically peculiar star chi Lupi
taken by the Goddard High Resolution Spectrograph in echelle mode are
presented. Thirty-six intervals of the spectral region between 1249 and
2688 Å are covered with resolving powers in the range
75,000-93,000. Line identifications are provided, and the observed
spectra are compared with synthetic spectra calculated using the SYNTHE
program and associated line lists with changes to the line lists. The
significance of these spectra for the chi Lupi Pathfinder Project and
the closely related atomic physics effort is discussed in a companion
paper.
Title: Estimation of Mass-Loss Rates from Emission Line
Profiles in the UV Spectra of Cool Stars
Authors: Carpenter, K. G.; Robinson, R. D.; Harper, G. M.
Affiliation: AA(NASA Goddard Space Flight Center), AB(NASA
Goddard Space Flight Center), AC(Colorado Univ.)
Publication: Technical Report, NASA Goddard Space Flight Center
Greenbelt, MD United States
Publication Date: 01/1999
Category: Astrophysics
Origin: STI
NASA/STI Keywords: COOL STARS, RADIATIVE TRANSFER, SUPERGIANT STARS,
ULTRAVIOLET SPECTRA, ULTRAVIOLET ASTRONOMY, STELLAR
WINDS, STELLAR MASS EJECTION, CHROMOSPHERE, EMISSION
SPECTRA, STELLAR SPECTRA, STELLAR MASS
Bibliographic Code: 1999STIN...0027505C
Abstract
The photon-scattering winds of cool, low-gravity stars (K-M giants and
supergiants) produce absorption features in the strong chromospheric
emission lines. This provides us with an opportunity to assess important
parameters of the wind, including flow and turbulent velocities, the
optical depth of the wind above the region of photon creation, and the
star's mass-loss rate. We have used the Lamers et al. Sobolev with Exact
Integration (SEI) radiative transfer code along with simple models of
the outer atmospheric structure to compute synthetic line profiles for
comparison with the observed line profiles. The SEI code has the
advantage of being computationally fast and allows a great number of
possible wind models to be examined. We therefore use it here to obtain
initial first-order estimates of the wind parameters. More
sophisticated, but more time-consuming and resource intensive
calculations will be performed at a later date, using the SEI-deduced
wind parameters as a starting point. A comparison of the profiles over a
range of wind velocity laws, turbulence values, and line opacities
allows us to constrain the wind parameters, and to estimate the
mass-loss rates. We have applied this analysis technique (using lines of
Mg II, 0 I, and Fe II) so far to four stars: the normal K5-giant alpha
Tau, the hybrid K-giant gamma Dra, the K5 supergiant lambda Vel, and the
M-giant gamma Cru. We present in this paper a description of the
technique, including the assumptions which go into its use, an
assessment of its robustness, and the results of our analysis.
Title: The outer atmosphere of Tau - II. Fluorescent lines
Authors: McMurry, A. D.; Jordan, C.; Carpenter, K. G.
Affiliation: AA(Department of Physics (Theoretical Physics),
University of Oxford, 1 Keble Road, Oxford OX1 3NP),
AB(Department of Physics (Theoretical Physics),
University of Oxford, 1 Keble Road, Oxford OX1 3NP),
AC(Laboratory for Astronomy and Solar Physics, Code
681, NASA-GSFC, Greenbelt, MD 20771, USA)
Publication: Monthly Notices of the Royal Astronomical Society,
Volume 302, Issue 1, pp. 48-58.
Publication Date: 01/1999
Origin: MNRAS
Abstract Copyright: (c) 1998, Royal Astronomical Society
DOI: 10.1046/j.1365-8711.1999.02077.x
Bibliographic Code: 1999MNRAS.302...48M
Abstract
The Goddard High Resolution Spectrograph (GHRS) on the Hubble Space
Telescope has been used to observe alpha Tau (K5 III). The resulting
spectra contain many sharp fluorescent lines. Most of these have been
identified as lines of Fe ii, Ca ii and H2, radiatively
excited by H Lyalpha. The chromospheric model developed in an
accompanying paper has been used to calculate the fluxes in these lines.
The Ca ii lines have been modelled with a full radiative transfer
calculation, but the Fe ii and H2 systems are more complex
and, for these, a simpler calculation has been made. Overall, the trend
in the Fe ii line fluxes provides evidence for a multicomponent model of
the atmosphere, a chromosphere with intrusions of hotter material or
vice versa. The hotter material could be in shocks propagating through
the chromosphere. Comparisons of the observed and calculated fluxes of
individual lines of Fe ii show that some atomic data need to be
improved. The analysis of the H2 lines is restricted by a
lack of suitable molecular data. The two observed Ca ii lines are
reproduced to within a factor of 2.
Title: Echelle Spectroscopy of Interstellar Absorption
toward MU Columbae with the Goddard High Resolution
Spectrograph
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.;
Boggess, A.; Carpenter, K. G.; Ebbets, D. C.;
Hutchings, J. B.; Jura, M.; Leckrone, D. S.;
Linsky, J. L.; Maran, S. P.; Savage, B. D.;
Smith, A. M.; Trafton, L. M.; Walter, F. M.;
Weymann, R. J.; Howk, J. C.; Snow, M.; Ake, T. B.;
Sembach, K. R.
Publication: The Astronomical Journal, Volume 117, Issue 1, pp.
400-409.
Publication Date: 01/1999
Origin: AJ
AJ Keywords: KEY WORDS: ISM: ABUNDANCES, ISM: GENERAL, STARS:
ABUNDANCES
Abstract Copyright: (c) 1999: The American Astronomical Society
DOI: 10.1086/300673
Bibliographic Code: 1999AJ....117..400B
Abstract
Goddard High Resolution Spectrograph echelle-mode observations of the
interstellar absorption lines of Mg II, Si IV, C IV, and N V toward mu
Columbae (HD 38666) are presented. The observations have a spectral
resolution of 3.5 km s^-1 and signal-to-noise ratios (S/Ns) of 20-200.
The mu Col sight line (l=237.3d, b=-27.1d, d=0.40 kpc, z=-0.18 kpc)
extends though the Local Bubble and the warm neutral, warm ionized, and
hot ionized phases of the interstellar medium (ISM). The high-ionization
column densities toward mu Col are log N(Si IV)=12.16+/-0.05, log N(C
IV)=12.88+/-0.02, and logN(N V)=11.8-12.3. Profile fits to Copernicus
satellite measures of O VI absorption toward mu Col yield log N(O
VI)=13.82+/-0.01 and b=38.7 km s^-1. This implies N(C IV)/N(O
VI)=0.11+/-0.01, which is typical of the values found for the hot ISM of
the Galactic disk. The O VI profile is twice as broad as the C IV and N
V profiles, even though these species have roughly similar average
velocities. Some of the C IV, N V, and O VI absorption toward mu Col may
occur at the interface of the Local Cloud and Local Bubble, although
additional contributions to these ions probably also occur in more
distant gas along the sight line. A substantial part of the Si IV
absorption likely arises in warm photoionized gas in an H II region
surrounding mu Col. The profile width differences among the
high-ionization lines of C IV, N V, and O VI could be produced if the
line of sight passes through a highly evolved supernova remnant. The
observations for mu Col and for other stars observed at high resolution
with the GHRS reveal that multiple gas types (warm and hot) contribute
to the absorption by the highly ionized atoms along both nearby and
distant sight lines. Disentangling the relative contributions from the
different gas types requires high-resolution and high-S/N observations.
The Mg II observations, combined with a solar Mg reference abundance,
imply that the Mg depletion toward mu Col is -0.31 dex. As observed for
other sight lines through the warm neutral medium, the gas-phase
observations of Mg, when combined with results for Fe and Si, suggest
that Mg and Fe are more deficient from the gas phase than one would
expect if these elements are only contained in silicate dust grains.
Title: Winds and mass-loss from evolved, low-gravity cool
stars.
Authors: Carpenter, K. G.; Robinson, R. D.
Publication: New Astron. Rev., Vol. 43, No. 6 - 7, p. 471 - 472
Publication Date: 00/1999
Origin: ARI
ARI Keywords: Cool Stars: Stellar Winds, Cool Stars: Mass Loss
DOI: 10.1016/S1387-6473(99)00101-3
Bibliographic Code: 1999NewAR..43..471C
Abstract
The authors summarize results from several programs utilizing the
Goddard High Resolution Spectrograph on the Hubble Space Telescope to
study winds and mass-loss from evolved, low-gravity cool stars. They
have found that: (i) the photons for thermally and fluorescently excited
UV emission lines are created below the region of wind acceleration,
(ii) the self-reversals in optically thick emission lines indicate an
outflowing wind with mean velocities of 9 - 25 km/s, (iii) the profiles
of optically thin emission lines indicate a mean chromospheric
macroturbulence of 24 - 35 km/s, anisotropically distributed along the
radial-tangential directions, (iv) significant emission from hot
material (≈105K) is seen in both non-coronal and hybrid
stars to the right of the Linsky-Haisch dividing line, (v) the weakness
of Fe II emission lines in the carbon stars, combined with the presence
of the Fe I 2807 Å feature only in carbon stars, suggests that the
ionization fraction of iron is significantly lower in the outer
atmospheres of carbon stars than in O-rich stars, and (vi) Fe II line
profile variations indicate changes in mass-loss rate and wind opacity
on a timescale of several years in two typical late-type, low-gravity
stars.
Title: The Chromosphere, Wind, and Mass-Loss Rate of lambda
Velorum (K5 Ib) as Revealed by UV Emission Line
Profiles
Authors: Carpenter, K. G.; Robinson, R. D.; Harper, G. M.;
Bennett, P. D.; Brown, A.; Mullan, D. J.
Affiliation: AA(NASA/GSFC), AB(IACS/CUA), AC(CASA/UCO),
AD(CASA/UCO), AE(CASA/UCO), AF(Bartol/UDE)
Publication: American Astronomical Society, 193rd AAS Meeting,
\#45.02; Bulletin of the American Astronomical
Society, Vol. 30, p.1317
Publication Date: 12/1998
Origin: AAS
Abstract Copyright: (c) 1998: American Astronomical Society
Bibliographic Code: 1998AAS...193.4502C
Abstract
The Goddard High Resolution Spectrograph (GHRS) on the HST has been used
to acquire high-quality UV spectra of the nearby K-supergiant lambda
Velorum. These spectra contain a wide variety of chromospheric emission
lines, many of which are self-reversed by wind absorption, and thus
allow us to probe the structure of both the chromosphere and wind. The
observed line widths, positions, and fluxes indicate a chromosphere with
a mean log n_e ~ 8.9 +/- -0.2 cm(-3) , a turbulence (indicated by line
cores with ~ 25 km s(-1) Doppler widths) greatly in excess of the
photospheric value, and no general systematic flows (i.e. the wind
acceleration appears to occur above the region of photon creation). We
compare synthetic Fe II line profiles from the approximate Lamers et al.
(1987) Sobelev with Exact Integration (SEI) method, and from an exact
comoving frame CRD calculation, with the observations. The width and
shape of the wind self-absorptions implies a terminal velocity of 29--33
km s(-1) , and a wind turbulence of ~ 9-21 km s(-1) . We find that the
wind in the 1994 GHRS observations can be described by a model with an
acceleration parameter beta ~ 0.9 and a mass-loss rate of ~ 3 x 10(-9)
Msun yr(-1) . However, this model is not consistent with the
VLA 3.6 cm radio continuum flux observed in 1997.
Title: The Mass of the Cepheid Binary V636 Scorpii
Authors: Böhm-Vitense, E.; Evans, N. R.; Carpenter, K.;
Albrow, Michael D.; Cottrell, P. L.; Robinson, R.;
Beck-Winchatz, B.
Publication: The Astrophysical Journal, Volume 505, Issue 2, pp.
903-909.
Publication Date: 10/1998
Origin: APJ
ApJ Keywords: STARS: BINARIES: SPECTROSCOPIC, STARS: VARIABLES:
CEPHEIDS, STARS: EVOLUTION, STARS: INDIVIDUAL:
CONSTELLATION NAME: V636 SCORPII
Abstract Copyright: (c) 1998: The American Astronomical Society
DOI: 10.1086/306177
Bibliographic Code: 1998ApJ...505..903B
Abstract
The mass-luminosity relation for Cepheids depends on the degree of
mixing in their main-sequence progenitors. Masses of Cepheids can be
inferred by using different aspects of pulsation theory. These methods
have in the past led to diverging results, showing that something was
wrong in either evolution theory or pulsation theory or both. For some
binary Cepheids dynamical masses, which are independent of pulsation and
evolution theories, can be determined. V636 Sco is one of a handful of
Cepheid binaries whose companions are bright enough in the ultraviolet
that orbital radial velocities can be measured. We have here attempted
to determine the radial velocity of the companion V636 Sco B to the
Cepheid V636 Sco A by means of two Hubble Space Telescope (HST) spectra
taken at phases of minimum and maximum Cepheid orbital velocities. The
ratio of the orbital velocity of the companion and the Cepheid (which is
the inverse of their mass ratio) came out to be 1.25 +/- 0.17. V636 Sco
B has a spectral type B9.5 V, for which we expect a stellar mass of 2.5
M_o. For the Cepheid we thus determine a mass of 3.1 +/- 0.4
M_o, which is surprisingly low. If true, such a low mass would
indicate an extremely large amount of excess mixing, which is very
unlikely. We discuss the likely possibility that V636 Sco B may itself
be a binary with an unseen secondary, in which case the mass derived
from the two measurements discussed above is not correct. Although the
error limits for the mass of each Cepheid are rather large, the combined
mass-luminosity relation for all Cepheids studied by us so far by means
of HST spectra indicates excess mixing corresponding to core convective
overshoot by 0.25 to about 0.5 pressure scale height in the
main-sequence progenitors of the Cepheids. Based on observations made
with the NASA/ESA Hubble Space Telescope, obtained at the Space
Telescope Science Institute, which is operated by the Association of
Universities for Research in Astronomy, Inc., under NASA contract
NASS-26555.
Title: Toward a Mass for the High Luminosity Cepheid T MON
Authors: Evans, Nancy Remage; Robinson, Richard D.;
Carpenter, Kenneth G.; Vinko, Jozsef; Massa, Derck;
Wahlgren, Glenn M.
Affiliation: AA(SAO), AB(Catholic Univ. of America),
AC(NASA/GSFC), AD(Jate Univ.), AE(Hughes STX),
AF(Univ. of Lund)
Publication: American Astronomical Society, 192nd AAS Meeting,
\#82.04; Bulletin of the American Astronomical
Society, Vol. 30, p.1155
Publication Date: 09/1998
Origin: AAS
Abstract Copyright: (c) 1998: American Astronomical Society
Bibliographic Code: 1998AAS...192.8204E
Abstract
The long period (27(d) ) Cepheid T Mon was shown by Coulson (1983,
MNRAS, 203, 925) to have orbital motion. A full orbit has not yet been
observed since the first velocities nearly a century ago. However, the
ratio of the orbital velocity changes during the last decade provide the
mass ratio between the Cepheid and its hot companion. We have obtained
new ground-based velocities of the Cepheid which constrain the orbital
velocity amplitude. To measure the companion velocities, we have IUE
high resolution spectra and also a Hubble Space Telescope Goddard High
Resolution Spectrograph spectrum (1840 to 1880 Angstroms). Use of the
new data to constrain the mass of the Cepheid will be discussed.
Title: Goddard High-Resolution Spectrograph Observations of
Cool Low-Gravity Stars. IV. A Comparison of the K5
III Stars alpha Tauri and gamma Draconis
Authors: Robinson, Richard D.; Carpenter, Kenneth G.;
Brown, Alexander
Publication: Astrophysical Journal v.503, p.396
Publication Date: 08/1998
Origin: APJ
ApJ Keywords: STARS: CHROMOSPHERES, STARS: INDIVIDUAL
CONSTELLATION NAME: ALPHA TAURI, STARS: INDIVIDUAL
CONSTELLATION NAME: GAMMA DRACONIS, STARS:
LATE-TYPE, STARS: MASS LOSS, ULTRAVIOLET: STARS
Abstract Copyright: (c) 1998: The American Astronomical Society
DOI: 10.1086/305971
Bibliographic Code: 1998ApJ...503..396R
Abstract
The Goddard High-Resolution Spectrograph (GHRS) has observed the K5 III
star alpha Tau in the 2330 Angstroms region on three separate occasions.
These spectra show marked changes with time, with the UV continuum
varying by a factor of 2, and with the emission lines changing in flux
by 30% or more, with the amount of change dependent upon the opacity of
the line. The variations suggests a restructuring of the atmosphere
rather than simply a change in the surface area covered by chromospheric
material. Surprisingly, there was no detectable change in the
chromospheric turbulence on timescales of hours or years. On average,
the lower part of the atmosphere was found to be fairly static, with a
slight infall of 1-2 km s-1. At higher altitudes, probed by observation
of the stronger Fe II lines as well as of the O I (UV 2) and Mg II (UV
1) resonance lines, there is evidence for the acceleration of a slow
wind, similar to that seen in the M giants gamma Cru and mu Gem. This
wind is much less massive than for the later type giants, however, since
its effects are seen in only the most optically thick of the Fe II
lines. Comparison of the alpha Tau observations with similar data for
the K5 III hybrid star gamma Dra shows remarkable similarity in the
photosphere and lower chromosphere. Both stars have pronounced UV
continua, identical turbulences and chromospheric densities, and very
similar line fluxes and profiles for all lines formed in the lower
chromosphere, including C II], Co I, Si II], and Fe II. A deep exposure
near 1500 Angstroms also shows the first evidence for hot plasma in the
atmosphere of alpha Tau through the detection of the C IV (UV 1) doublet
with a surface flux about 30% of that observed in gamma Dra. Most of the
evidence for the stellar wind is in the Mg II (UV 1) and O I (UV 2)
resonance lines. Modeling these lines using the Sobolev with Exact
Integration (SEI) radiative transfer code shows that the wind in gamma
Dra accelerates faster and reaches a higher terminal velocity than does
the wind in alpha Tau. However, the wind turbulent velocity in gamma Dra
is only about one-third of the value seen in alpha Tau. We conclude that
the observations support the suggestion by Judge & Stencel that the
processes that heat the chromosphere are distinct from those that drive
the stellar winds.
Title: An Ultraviolet Spectral Atlas of 10 Lacertae
Obtained with the Goddard High Resolution
Spectrograph on the Hubble Space Telescope
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.;
Boggess, A.; Carpenter, K. G.; Ebbets, D. C.;
Hutchings, J. B.; Jura, M.; Leckrone, D. S.;
Linsky, J. L.; Maran, S. P.; Savage, B. D.;
Smith, A. M.; Trafton, L. M.; Walter, F. M.;
Weymann, R. J.; Snow, M.; Ake, T. B.; Hogen, R. H.
Affiliation: AA(Laboratory for Atmospheric and Space Physics,
Campus Box 392, University of Colorado, Boulder, CO
AB(Laboratory for Astronomy and Solar Physics, Code
681, NASA Goddard Space Flight Center, Greenbelt, MD
Astrophysics and Space Sciences, C-0111, University
of California, San Diego, La Jolla, CA 92093-0111
AE(Laboratory for Astronomy and Solar Physics, Code
681, NASA Goddard Space Flight Center, Greenbelt, MD
Aerospace & Technologies Corporation, AR1, P.O. Box
AG(Dominion Astrophysical Observatory, 5071 West
Saanich Road, Victoria, BC V8X 4M6, Canada;
and Astronomy, UCLA, Los Angeles, CA 90095-1562
Astronomy and Solar Physics, Code 681, NASA Goddard
Space Flight Center, Greenbelt, MD 20771;
Box 440, University of Colorado, Boulder, CO
80309-0440 and National Institute of Standards and
Sciences Directorate, Code 600, NASA Goddard Space
Flight Center, Greenbelt, MD 20771;
Astronomy, University of Wisconsin, 475 North
Charter Street, Madison, WI 53706;
Astronomy and Solar Physics, Code 681, NASA Goddard
Space Flight Center, Greenbelt, MD 20771;
Observatory and Department of Astronomy, University
of Texas at Austin, Austin, TX 78712;
and Astronomy, State University of New York, Stony
AP(Observatories of the Carnegie Institution of
Washington, 813 Santa Barbara Street, Pasadena, CA
Atmospheric and Space Physics, Campus Box 392,
University of Colorado, Boulder, CO 80309-0392
Computer Sciences Corporation, NASA Goddard Space
Flight Center, Greenbelt, MD 20771;
and Space Physics, Campus Box 392, University of
Colorado, Boulder, CO 80309-0392
Publication: The Astronomical Journal, Volume 116, Issue 2, pp.
941-971.
Publication Date: 08/1998
Origin: AJ
AJ Keywords: ATLASES, STARS: EARLY-TYPE, STARS: INDIVIDUAL:
CONSTELLATION NAME: 10 LACERTAE
DOI: 10.1086/300446
Bibliographic Code: 1998AJ....116..941B
Abstract
Observations of the narrow-lined O-type star 10 Lacertae taken with the
Goddard High Resolution Spectrograph in 1992 November are presented. The
spectra cover the wavelength range 1181-1777 Å with a resolution
of 15 km s^-1 and signal-to-noise ratio greater than 100:1. Absorption
lines arising in the interstellar medium, the photosphere, and the
stellar wind are identified and discussed.
Title: Skull of a Jurassic ankylosaur (Dinosauria)
Authors: Carpenter, Kenneth; Miles, Clifford; Cloward, Karen
Publication: Nature, Volume 393, Issue 6687, pp. 782-783 (1998).
Publication Date: 06/1998
Origin: NATURE
Abstract Copyright: (c) 1998: Nature
DOI: 10.1038/31684
Bibliographic Code: 1998Natur.393..782C
Abstract
The origin and early evolution of many major dinosaur groups are poorly
known because specimens are rare. One of these groups, the Ankylosauria,
or armour-plated dinosaurs, is best known from well-preserved specimens
from the Upper Cretaceous period of Asia and North America. Here we
describe a well-preserved skull of an earlier, Late Jurassic ankylosaur,
which will be important in clarifying the early history of this group.
The specimen, Gargoyleosaurus parkpini gen. et sp. nov., was collected
from the Upper Jurassic Morrison Formation of Wyoming, USA. Despite its
geological age, the skull shows features seen in Late Cretaceous
ankylosaurs, including fusion of bone armour to the surface of the skull
and mandible and closure of two skull openings, the antorbital and upper
temporal fenestrae. The new taxon also has characters common to the two
ankylosaur families, the Ankylosauridae and Nodosauridae, supporting the
proposal that the Ankylosauria originated from a single ancestor.
Nevertheless, specialized characters place Gargoyleosaurus as the most
primitive, or basal, member of the Ankylosauridae.
Title: Simple models for dynamic hysteresis which add
frequency-dependent losses to static models
Authors: Carpenter, K. H.
Publication: IEEE Transactions on Magnetics, vol. 34, issue 3,
pp. 619-622
Publication Date: 05/1998
Origin: CROSSREF
DOI: 10.1109/20.668054
Bibliographic Code: 1998ITM....34..619C
Abstract
Not Available
Title: Large Variations in the Winds of Single Cool Giants:
lambda Velorum and gamma Crucis
Authors: Mullan, D. J.; Carpenter, K. G.; Robinson, R. D.
Publication: Astrophysical Journal v.495, p.927
Publication Date: 03/1998
Origin: APJ
ApJ Keywords: STARS: MASS LOSS, STARS: LATE-TYPE, ULTRAVIOLET:
STARS, LINE: PROFILES
Abstract Copyright: (c) 1998: The American Astronomical Society
DOI: 10.1086/305340
Bibliographic Code: 1998ApJ...495..927M
Abstract
UV spectra of the "noncoronal" single K supergiant lambda Vel and of the
single M giant gamma Cru obtained with IUE and the Hubble Space
Telescope at various epochs indicate that the profiles of many lines
formed in the wind exhibit striking alterations in shape with time. We
parameterize the wind profiles in terms of an empirical optical depth
tau emp by reflecting the red wing about line center and comparing the
reflected intensity with that of the blue wing. In the lambda Vel wind
the terminal velocity v∞ was found to be close to 40 km s-1 in
1978, 1982, and 1994, but was at least 20 km s-1 greater in 1990. The
faster wind in 1990 also had a total optical depth that was a factor of
2-6 times greater than at the other epochs.
Title: Classical Cepheid Masses: U Aquilae
Authors: Evans, Nancy Remage; Boehm-Vitense, Erika;
Carpenter, Kenneth; Beck-Winchatz, Bernhard;
Robinson, Richard
Publication: Astrophysical Journal v.494, p.768
Publication Date: 03/1998
Origin: APJ
ApJ Keywords: STARS: BINARIES: SPECTROSCOPIC, STARS: INDIVIDUAL
CONSTELLATION NAME: U AQUILAE, STARS: VARIABLES:
CEPHEIDS, STARS: FUNDAMENTAL PARAMETERS
DOI: 10.1086/305242
Bibliographic Code: 1998ApJ...494..768E
Abstract
We have obtained medium-resolution spectra ( lambda / Delta lambda ~
20,000) of the hot binary companion to the classical Cepheid U Aql with
the Goddard High Resolution Spectrograph on the Hubble Space Telescope
(HST). These have been used to determine the orbital velocity amplitude.
Combining this with the orbital velocity amplitude of the Cepheid from
the ground-based orbit and the mass of the companion inferred from its
spectral type, we measure a mass of the Cepheid of 5.1 +/- 0.7 Mo.
We discuss the full sample of Cepheids for which we have determined
masses with HST (S Mus, V350 Sgr, Y Car, and U Aql) and also SU Cyg
(mass from IUE). The HST masses are in agreement with the luminosities
predicted by recent evolutionary tracks with moderate overshoot. This
comparison, however, may be altered by reassessment of Cepheid distances
based on Hipparcos parallaxes.
Title: On Chromospheric Heating Mechanisms of ``Basal
Flux'' Stars
Authors: Judge, P. G.; Carpenter, K. G.
Publication: Astrophysical Journal v.494, p.828
Publication Date: 02/1998
Origin: APJ
ApJ Keywords: SHOCK WAVES, STARS: CHROMOSPHERES, STARS: INTERIORS,
SUN: CHROMOSPHERE
Abstract Copyright: (c) 1998: The American Astronomical Society
DOI: 10.1086/305232
Bibliographic Code: 1998ApJ...494..828J
Abstract
Several pieces of evidence have been pieced together over recent years
to support the notion that the chromospheric emission measured from
stars with convection zones results in part from the upward propagation
and dissipation of acoustic waves. One argument, based on a statistical
analysis of available UV data of such stars across the H-R diagram,
suggests the presence of an omnipresent "basal" level of chromospheric
heating, which has been postulated as resulting from nonlinear acoustic
wave heating. However, with few exceptions, no studies have been made
that test more directly the intrinsically dynamic nature of this
shock-heating mechanism. Therefore, in order to search for more direct
signatures of such upward-propagating shock waves in lines of C II, we
examined Goddard High-Resolution Spectrograph spectra of several evolved
stars that have "basal" levels of activity. No evidence is found to
support the presence of such waves as a dominant component of the
heating mechanism. Instead, behavior reminiscent of the solar transition
region is seen, suggesting a magnetic heating mechanism for these stars.
We conclude that upward-propagating shock waves do not dominate the
observed radiative losses from chromospheres of stars exhibiting typical
"basal" behavior, and we suggest that the nonmagnetic origin of the
basal components of all convective stars must be called into question.
New solar data from the SUMER instrument on SOHO also suggest problems
with the acoustic-wave interpretation, although further work is
warranted. In the course of this work, we also found a simple
explanation for previously noted discrepancies between calculated and
observed ratios of C II lines in the spectrum of alpha Ori.
Title: The Goddard High Resolution Spectrograph:
Post-COSTAR Characteristics
Authors: Robinson, R. D.; Ake, T. B.; Lindler, D. J.;
Heap, S. R.; Carpenter, K. G.; Leckrone, D. S.;
Maran, S. P.; Smith, A. M.; Brandt, J. C.;
Beaver, E. A.; Boggess, A.; Ebbets, D. C.;
Hutchings, J. B.; Jura, M.; Linsky, J. L.;
Savage, B. D.; Trafton, L. M.; Walter, F. M.;
Weymann, R. J.
Affiliation: AA(Astronomy Programs, Computer Sciences
Corporation, Code 681/CSC, Goddard Space Flight
Center, Greenbelt, MD 20771;
Computer Sciences Corporation, Code 681/CSC, Goddard
Space Flight Center, Greenbelt, MD 20771;
Concepts, Code 681, NASA/Goddard Space Flight
Center, Greenbelt, MD 20771;
Astronomy and Solar Physics, Code 681 NASA/Goddard
Space Flight Center, Greenbelt, MD 20771;
Astronomy and Solar Physics, Code 681 NASA/Goddard
Space Flight Center, Greenbelt, MD 20771;
Astronomy and Solar Physics, Code 681 NASA/Goddard
Space Flight Center, Greenbelt, MD 20771;
Astronomy and Solar Physics, Code 681 NASA/Goddard
Space Flight Center, Greenbelt, MD 20771;
Astronomy and Solar Physics, Code 681 NASA/Goddard
Space Flight Center, Greenbelt, MD 20771;
Atmospheric and Space Physics, Campus Box 392,
University of Colorado, Boulder, CO 80309-0392
Astrophysics and Space Sciences, C-011, University
of California, San Diego, La Jolla, CA 92093-0111),
AK(Code 440, NASA/Goddard Space Flight Center,
Greenbelt, MD 20771;
Systems Group, P. O. Box 1062, AR1, Boulder, CO
Astrophysical Observatory, 5071 West Saanich Road,
Victoria, BC, V8X 4M6, Canada;
University of California, Los Angeles, CA 90024;
for Laboratory Astrophysics, University of Colorado
and National Institute of Standards and Technology,
AP(Department of Astronomy, University of Wisconsin,
475 North Charter Street, Madison, WI 53706;
Observatory and Astronomy Department, University of
AR(Department of Earth and Space Sciences, State
University of New York, Stony Brook, NY 11794-2100
the Carnegie Institute of Washington, 812 Santa
Publication: The Publications of the Astronomical Society of the
Pacific, Volume 110, Issue 743, pp. 68-78.
Publication Date: 01/1998
Origin: PASP
PASP/ApJ Keywords: INSTRUMENTATION: SPECTROGRAPHS
Abstract Copyright: The Astronomical Society of the Pacific
DOI: 10.1086/316116
Bibliographic Code: 1998PASP..110...68R
Abstract
We review changes to the characteristics of the Goddard High Resolution
Spectrograph (GHRS) which resulted from the installation of the
Corrective Optics Space Telescope Axial Replacement (COSTAR) on the
Hubble Space Telescope. The introduction of two new optical elements
into the light path altered the spectral distribution of the light,
decreasing the amount of light striking the instrument by about 30% at
wavelengths greater than 1200 Å and effectively eliminated all
radiation at wavelengths less than 1130 Å. However, at the longer
wavelengths the improved focus offset this loss when the Large Science
Aperture (LSA) was used and increased the overall throughput of the
Small Science Aperture (SSA) by a factor of 2. The improved focus also
enhanced the spectral resolution of LSA observations and improved the
ability of the instrument to observe in crowded fields.
Title: Extraction of Atmospheric Water on Mars for the Mars
Reference Mission
Authors: Adan-Plaza, Sergio; Carpenter, Kirsten; Elias, Laila;
Grover, Rob; Hilstad, Mark; Hoffman, Chris;
Schneider, Matt; Br{\"{u}}ckner, Adam
Affiliation: AA(Washington Univ.), AB(Washington Univ.),
AC(Washington Univ.), AD(Washington Univ.),
AE(Washington Univ.), AF(Washington Univ.),
AG(Washington Univ.), AH(Washington Univ.)
Publication: HEDS-UP Mars Exploration Forum, p. 171
Publication Date: 01/1998
Category: Lunar and Planetary Exploration
Origin: STI
NASA/STI Keywords: ADSORPTION, ELECTROLYSIS, LIFE SUPPORT SYSTEMS, MARS
ATMOSPHERE, WATER, WATER VAPOR, ZEOLITES, MANNED
MARS MISSIONS, MICROWAVES, LIQUID HYDROGEN, FANS,
PRESSURE DROP
Bibliographic Code: 1998heds.conf..171A
Abstract
The University of Washington has designed an in situ resource
utilization system to provide water to a life support system in the
laboratory module of the NASA Reference Mission to Mars. This system,
the Water Vapor Adsorption Reactor (WAVAR), extracts water vapor from
the Martian atmosphere by adsorption in a bed of type 3A zeolite
molecular sieve. The zeolite 3A adsorbs the water vapor until nearly
saturated and is then heated within a sealed chamber by microwave
radiation to drive off the water for collection. The water vapor flows
to a condenser where it freezes and is later liquefied for use in the
life support system. In the NASA Reference Mission, water, methane, and
oxygen are produced for life support and propulsion via the
Sabatier/Electrolysis process from seed hydrogen brought from Earth and
Martian atmospheric carbon dioxide. In order for the WAVAR system to be
compatible with the NASA Reference Mission, its mass must be less than
that of the seed hydrogen and cryogenic tanks apportioned for life
support in the Sabatier/Electrolysis process. The WAVAR system is
designed for atmospheric conditions observed by the Viking missions,
which measured an average global atmospheric water vapor concentration
of approx. 2 x 10-6kg/cubic meter. WAVAR performance is
analyzed taking into consideration hourly and daily fluctuations in
Martian ambient temperature and the corresponding effects on zeolite
performance.
Title: Two-Component Winds from Luminous Late-Type Stars
Authors: Airapetian, V. S.; Offman, L.; Robinson, R.;
Carpenter, K.; Davila, J.
Affiliation: AA(CSC/GSFC), AB(Hughes STX/GSFC), AC(Catholic Univ.
of America), AD(GSFC/NASA)
Publication: American Astronomical Society Meeting, 191, \#125.05
Publication Date: 01/1998
Origin: AAS
Abstract Copyright: (c) 1997: American Astronomical Society
Bibliographic Code: 1998BAAS...30..760A
Abstract
We present the results of a magnetohydrodynamic (MHD) simulation of
winds from luminous late-type stars using a 2.5D, non-linear MHD
computer code. In this simulation we assume that the wind is generated
within a hydrostatic atmosphere with an initial isothermal pressure
scale height of 0.072 Rstar and a radial magnetic field. We
also assume a transverse density gradient which we we refer to as a
``chromospheric hole''. Tortional Alfven waves are generated at the
stellar surface by a forcing function having a single frequency, which
is comparable to the turn-over frequency of convective cells in giant
stars. To ensure that we are accurately assessing the terminal velocity
of the wind, we carried out the calculations to a height of 20 stellar
radii and a time period of more than 180 Alfven transit times, which
ensures that a steady state has been reached. In the higher density (low
Alfven velocity) regions outside of the ``chromospheric hole'' the
Alfven waves are freely propagating. Ponderomotive forces associated
with these waves drive radial, compressive motions and contribute to
stellar wind acceleration. The compressive motions then excite slow
magnetosonic waves which non-linearly steepen into solitary waves that
propagate on top of a background flow similar to the case of solar
coronal holes. This produces a fast (40-80 km/s) and relatively dense
component of the wind. In the lower density ``chromospheric hole''
region the Alfven waves are strongly reflected and produce an outflow
with both radial and azimuthal velocities which are ~ 10% of the local
Alfven speed. This component of the wind is slow ( ~ 10-30 km/s) and
less dense than the wind initiated outside of the hole. Depending on the
magnetic topology in the atmosphere of a luminous late - type star, we
may therefore expect either one (fast) or two components to the wind.
Our results are consistent with recent observations of two discrete
components to the wind in the K5 III hybrid star gamma Dra. These
components were detected in the Mg II h and k resonance lines and had
velocities of 67 and 30 km/s, with the higher velocity component having
a mass loss rate which is 10 times that of the slower speed wind.
Title: The Structure of the Outer Atmosphere and Wind of
lambda Vel
Authors: Carpenter, Kenneth G.
Affiliation: AA(Laboratory for Astronomy and Solar Physics, Code
681 NASA-GSFC, Greenbelt, MD 20771 USA,
Publication: Asymptotic Giant Branch Stars, IAU Symposium 191
Poster Session, \#P2-06, held in Montpellier, France,
Aug 28 - Sept 1, 1998.
Publication Date: 00/1998
Origin: AUTHOR
Bibliographic Code: 1998IAUS..191P.206C
Abstract
The Goddard High Resolution Spectrograph (GHRS) on the Hubble Space
Telescope (HST) has been used to acquire high-quality UV spectra of the
nearby K-supergiant lambda Vel, a star most likely in an evolutionary
stage either immediately preceeding or just entering the AGB. These
spectra contain a wide variety of chromospheric emission lines, as well
as a strong chromospheric continuum, and thus allow us to probe
conditions in the the atmospheric region within which the stellar wind
and associated mass-loss are initiated. In addition, the profiles of
many of these emission lines are influenced by absorption occurring
within the wind and are thus good diagnostics of the radial structure of
that wind. Comparison of synthetic and observed spectra allows estimates
of the wind turbulence, acceleration, opacity, and mass-loss rate. We
present a summary of our analysis of these spectra, including: 1)
measurements of temperature, turbulence, and flow velocity versus height
in the chromosphere and wind, and 2) estimates of the mass-loss rate. It
is our hope that these observations will provide powerfull constraints
on theoretical models of chromospheric heating, wind acceleration, and
mass-loss in this and other red giant and supergiant stars.
Title: Winds and Mass-Loss from Evolved, Low-Gravity Cool
Stars
Authors: Carpenter, K. G.; Robinson, R. D.
Publication: Highlights of Astronomy Vol. 11A, as presented at
Joint Discussion 14 of the XXIIIrd General Assembly
of the IAU, 1997. Edited by Johannes Andersen.
Kluwer Academic Publishers, 1998., p.378
Publication Date: 00/1998
Origin: ADS
Bibliographic Code: 1998HiA....11..378C
Abstract
Not Available
Title: HST Observations of Carbon Stars
Authors: Carpenter, Kenneth G.; Robinson, R. D.;
Johnson, H. R.
Affiliation: AA(Laboratory for Astronomy & Solar Physics,
NASA-GSFC), AB(Astronomy Programs, Computer Sciences
Corporation), AC(Astronomy Department, Indiana
University)
Publication: ASP Conf. Ser. 154, The Tenth Cambridge Workshop on
Cool Stars, Stellar Systems and the Sun, Edited by
R. A. Donahue and J. A. Bookbinder, p.1578
Publication Date: 00/1998
Origin: AUTHOR
Keywords: CHROMOSPHERES, WINDS, STARS
Comment: ISBN: 1-886733-74-0
Bibliographic Code: 1998ASPC..154.1578C
Abstract
Ultraviolet spectra obtained with the Goddard High Resolution
Spectrograph (GHRS) on the HST of the carbon stars TX Psc, TW Hor, and
UU Aur are presented and compared with each other and with spectra of
the oxygen-rich cool giants mu Gem and 30 Her. For TX Psc, we discuss
the inferred outer atmospheric flow and turbulent velocities, the
relative and absolute strength of emission from C 2 and Fe 2, the
ionization fraction of iron, and variations of its spectrum with time.
We also discuss two fluorescence processes operating in the atmospheres
of carbon stars and compare in detail the Mg 2 profiles seen in both
carbon and O-rich stars.
Title: Atmospheric Dynamics of Luminous Late-Type Stars
Authors: Airapetian, V. S.; Ofman, L.; Robinson, R. D.;
Carpenter, K.; Davila, J.
Affiliation: AA(Computer Sciences Corporation, Science Programs,
NASA/GSFC, Greenbelt MD 20771), AB(Hughes STX,
NASA/GSFC, Greenbelt MD 20771), AC(Computer Sciences
Corporation, Science Programs, NASA/GSFC, Greenbelt
MD 20771), AD(LASP, NASA/GSFC, Greenbelt MD 20771),
AE(LASP, NASA/GSFC, Greenbelt MD 20771)
Publication: ASP Conf. Ser. 154, The Tenth Cambridge Workshop on
Cool Stars, Stellar Systems and the Sun, Edited by
R. A. Donahue and J. A. Bookbinder, p.1569
Publication Date: 00/1998
Origin: AUTHOR
Comment: ISBN: 1-886733-74-0
Bibliographic Code: 1998ASPC..154.1569A
Abstract
We present first results of magnetohydrodynamic (MHD) calculations of
winds from luminous late-type stars using an existing, 2.5D, non-linear
MHD code recently developed by Ofman & Davila (e.g., Ofman &
Davila 1997). We assume that the wind is initiated in a hydrostatic
atmosphere with an isothermal pressure scale height of 0.072 R* and a
``chromospheric hole'' modeled by a transverse density structure and a
radial magnetic field. To ensure that we are accurately assessing the
terminal velocity of the wind, we carried out the calculations to a
height of 20 stellar radii. We find that in the higher density (low
Alfven velocity) regions outside of the ``chromospheric hole'' the
Alfven waves are freely propagating. Ponderomotive forces associated
with these waves drive radial, compressive motions and contribute to
stellar wind acceleration. The compressive motions then excite slow
magnetosonic waves which non-linearly steepen into solitary waves that
propagate on top of a background flow. This situation is similar to
solar coronal hole models. In the lower density ``chromospheric hole''
region the Alfven wave are strongly reflected, and produce a substantial
outflow, with both radial and azimuthal velocities approaching the local
Alfven speed. Our results are in qualitative agreement with
observational signatures of winds in cool, luminous late-type stars.
Title: Searching for the Cause of Hybrid Star Activity
Authors: Robinson, Richard D.; Carpenter, Kenneth G.;
Brown, Alexander
Affiliation: AA(Science Programs, Computer Sciences Corporation),
AB(Laboratory for Astronomy & Solar Physics,
NASA-GSFC), AC(Astronomy Department, Indiana
University)
Publication: ASP Conf. Ser. 154, The Tenth Cambridge Workshop on
Cool Stars, Stellar Systems and the Sun, Edited by
R. A. Donahue and J. A. Bookbinder, p.1307
Publication Date: 00/1998
Origin: AUTHOR
Keywords: CHROMOSPHERES, WINDS, STARS
Comment: ISBN: 1-886733-74-0
Bibliographic Code: 1998ASPC..154.1307R
Abstract
UV spectra for a wide range of chromospheric diagnostics have been
obtained for the non-coronal giant alpha Tau and the `hybrid' star gamma
Dra using the Goddard High Resolution Spectrograph. These stars have
very similar spectral types and are very close to one another in mass,
luminosity, size, effective temperature and gravity. A detailed
comparison shows that the photosphere and chromosphere of the stars are
very similar. The two stars show the same level of UV continuum emission
and chromospheric turbulence and have Fe 2 emission profiles which are
nearly identical. The amount of transition region plasma, as measured by
the C 4 surface flux, is also nearly the same. The winds of these two
stars, however, are significantly different. Preliminary models based on
the O 1 (UV 2) and Mg 2 (UV 1) profiles show that the wind for alpha Tau
has a terminal velocity of ~30 km s^{-1} and a much slower acceleration
than the wind of gamma Dra, which has a terminal velocity of ~65 km
s^{-1}. However, despite the different wind properties, the mass loss
rate from these two stars is very similar.
Title: Fluorescence in the Chromosphere of alpha Tau (K5
III)
Authors: McMurry, A. D.; Jordan, C.; Carpenter, K. G.;
Robinson, R. D.
Affiliation: AA(Dept. of Physics (Theoretical Physics),
University of Oxford, UK), AB(Dept. of Physics
(Theoretical Physics), University of Oxford, UK),
AC(LASP, NASA-GSFC, Greenbelt, Maryland, USA),
AD(CSC, NASA-GSFC, Greenbelt, Maryland, USA)
Publication: ASP Conf. Ser. 154, The Tenth Cambridge Workshop on
Cool Stars, Stellar Systems and the Sun, Edited by
R. A. Donahue and J. A. Bookbinder, p.1293
Publication Date: 00/1998
Origin: AUTHOR
Keywords: CHROMOSPHERE, MODELLING, FLUORESCENCE
Comment: ISBN: 1-886733-74-0
Bibliographic Code: 1998ASPC..154.1293M
Abstract
The Goddard High Resolution Spectrograph (GHRS) on the Hubble Space
Telescope has been used to obtain spectra of alpha Tau covering many
parts of the uv spectrum between 1200AA and 2000AA. Here we concentrate
on the region between 1320AA and 1390AA, which is covered by 2 medium
resolution exposures. Most of the lines appearing in these spectra have
been identified, including 2 bands of fluorescent CO lines. Preliminary
modelling of these CO lines has been carried out, and the results are
compared with the observations.
Title: The Mass of the Beat Cepheid Y Carinae
Authors: Bohm-Vitense, E.; Beck-Winchatz, B.; Evans, N. R.;
Carpenter, K. G.; Robinson, R.
Publication: The Scientific Impact of the Goddard High Resolution
Spectrograph ASP Conference Series; Vol. 143; 1998;
ed. John C. Brandt; Thomas B. Ake; Carolyn Collins
Petersen, p.317
Publication Date: 00/1998
Origin: ADS
Bibliographic Code: 1998ASPC..143..317B
Abstract
Not Available
Title: The Mass of the Classical Cepheid V350 SGR
Authors: Evans, N. R.; Bohm-Vitense, E.; Beck-Winchatz, B.;
Carpenter, K.; Robinson, R.
Publication: The Scientific Impact of the Goddard High Resolution
Spectrograph ASP Conference Series; Vol. 143; 1998;
ed. John C. Brandt; Thomas B. Ake; Carolyn Collins
Petersen, p.313
Publication Date: 00/1998
Origin: ADS
Bibliographic Code: 1998ASPC..143..313E
Abstract
Not Available
Title: The Mass of the Classical Cepheid S MUSCAE
Authors: Evans, N. R.; Bohm-Vitense, E.; Beck-Winchatz, B.;
Carpenter, K.; Robinson, R.
Publication: The Scientific Impact of the Goddard High Resolution
Spectrograph ASP Conference Series; Vol. 143; 1998;
ed. John C. Brandt; Thomas B. Ake; Carolyn Collins
Petersen, p.309
Publication Date: 00/1998
Origin: ADS
Bibliographic Code: 1998ASPC..143..309E
Abstract
Not Available
Title: Cool Stars
Authors: Carpenter, K. G.
Publication: The Scientific Impact of the Goddard High Resolution
Spectrograph ASP Conference Series; Vol. 143; 1998;
ed. John C. Brandt; Thomas B. Ake; Carolyn Collins
Petersen, p.67
Publication Date: 00/1998
Origin: ADS
Bibliographic Code: 1998ASPC..143...67C
Abstract
Not Available
Title: The Dynamical and Beat Masses of the Beat Cepheid Y
Carinae
Authors: Bohm-Vitense, E.; Evans, N. R.; Carpenter, K.;
Winchatz, B. Beck-; Morgan, S.; Robinson, R.
Affiliation: AA(Univ. Washington, USA)
Publication: A Half Century of Stellar Pulsation Interpretation:
A Tribute to Arthur N. Cox, edited by Paul A.
Bradley and Joyce A. Guzik, Proceedings of a
Conference held in Los Alamos, NM 16-20 June 1997,
ASP Conference Series \#135, p. 280.
Publication Date: 00/1998
Origin: ADS
Bibliographic Code: 1998ASPC..135..280B
Abstract
The mass-luminosity relation for Cepheids depends on the degree of
excess mixing in their main sequence progenitors. The mass determination
for Cepheids with their known luminosities therefore determines the
degree of excess mixing in massive main sequence stars. We have
determined the dynamical mass of several Cepheids with blue companions.
Here we discuss the beat Cepheid Y Carinae. By means of HST, GHRS
spectra we measured the radial velocity of the B9.5 V companion Y Car B
at phases near minimum and maximum orbital radial velocities. The
orbital velocity amplitude ratio between the Cepheid and the hot
companion and thereby the mass ratio comes out to be 1.51 0.5, leading
to a mass of 3.8 1 1.2 solar masses. Taking the 3.8 solar masses at face
value this indicates excess mixing corresponding to convective overshoot
by about 1 pressure scale height, (see Bertelli et al.1986), but the
error limits are too large for a firm conclusion. The beat masses,
determined from the period ratios for the beat Cepheids, have puzzled
astronomers for a long time (see Cox 1980) because they came out around
1 to 2 solar masses, when the Cox-Tabor opacities were used for the
model calculations. Moskalik et al.(1992) showed that beat masses around
4 to 5 solar masses can now be derived, if the new OPAL opacities are
used instead. With the determination of the dynamical mass for Y Car A
we can now check the validity of the OPAL opacities more quantitatively
than was possible before. Using the model calculations incorporating the
OPAL opacities, and the observed effective temperature of Y Carinae we
determine for its beat mass a possible range of 3.75 < M/Ms < 4.0,
in very good agreement with the dynamical mass. This supports the
validity of the OPAL opacities, and also supports the conclusion about
the high degree of excess mixing in the main sequence progenitor of Y
Carinae A.
Title: Digging Deeper in the Coronal Graveyard
Authors: Ayres, Thomas R.; Brown, Alexander; Harper, G. M.;
Bennett, P. D.; Linsky, J. L.; Carpenter, K. G.;
Robinson, R. D.
Publication: Astrophysical Journal v.491, p.876
Publication Date: 12/1997
Origin: APJ
ApJ Keywords: STARS: CORONAE, STARS: LATE-TYPE, ULTRAVIOLET:
STARS, X-RAYS: STARS
Abstract Copyright: (c) 1997: The American Astronomical Society
DOI: 10.1086/304989
Bibliographic Code: 1997ApJ...491..876A
Abstract
Soft X-ray detections of stellar coronae (T ~ 106 K) are rare in the
giant branch redward of ~K1 III. We have conducted a less direct--but
more sensitive--search using the Hubble Space Telescope Goddard
High-Resolution Spectrograph to probe for far-ultraviolet proxies of the
hot coronal gas in representative "noncoronal" red giants. In every
target so far examined, we find weak but statistically significant Si IV
emission, as well as, commonly, C IV and, in some cases, N V. Si IV is
not affected by the CNO anomalies produced by the first dredge-up, which
can deplete the carbon abundance and weaken C IV. In the low-activity
giants, the lambda 1393 component of the Si IV doublet must be corrected
for sharp absorptions, which we believe are caused by carbon monoxide in
overlying cool material. The normalized flux ratios (R=f/f_{{bol}}) of
Si IV and X-rays among the "coronal" yellow giants (lying just blueward
of the "noncoronal" zone) fall on a uniform track,
R_{{X}}~R2_{{Si} {IV}} . In the noncoronal zone, however, the
Si IV index is nearly constant (R_{{Si} {IV}}~10^{-8}) , independent of
R_{{X}} (which ranges from ~10-8 to <~10-10). The mechanism that
diminishes X-ray activity in the red giants is highly sensitive to an as
yet unidentified stellar property. Photoelectric absorption by cool gas
might play a more important role than previously suspected, particularly
if hot magnetic loops are partly or completely buried in the
chromosphere.
Title: Pondering Puzzling Profiles: MG II Emission from
Carbon Stars
Authors: Carpenter, K. G.; Robinson, R. D.; Johnson, H. R.
Affiliation: AA(LASP/NASA-GSFC), AB(Catholic U. of America),
AC(Indiana U.)
Publication: American Astronomical Society, 191st AAS Meeting,
\#13.06; Bulletin of the American Astronomical
Society, Vol. 29, p.1230
Publication Date: 12/1997
Origin: AAS
Abstract Copyright: (c) 1997: American Astronomical Society
Bibliographic Code: 1997AAS...191.1306C
Abstract
We have obtained spectroscopic observations of the Mg II h & k
emission lines from three carbon stars, using the moderate resolution
(R>=20,000) G270M grating of the Goddard High Resolution Spectrograph
(GHRS) on the Hubble Space Telescope (HST). The emission profiles from
all three stars are very broad and heavily mutilated by overlying
absorption. The profiles from two of the stars, TX Psc (N0; C6,2) and TW
Hor (N0; C7,2), are very similar. However, the profiles from the third
star, UU Aur (N3; C5,3) are dramatically different from the other two
stars on the blue side, with strong emission persisting out to ~ -200
km/s (cf. to only weak emission out to ~ -100 km/s in TX Psc and TW
Hor). If the intrinsic (i.e. chromospheric) width of the emission in the
carbon stars is comparable to that in oxygen-rich giants, then the
spectra of the first two carbon stars are easily understood in terms of
additional overlying absorptions, but the amount of excess emission from
the blue side of the UU Aur profiles is difficult to explain. If, on the
other hand, the intrinsic width of the Mg II emission in the carbon
stars is more comparable to that of the supergiant oxygen-rich stars
(e.g. alpha Ori), then all the carbon stars have tremendous overlying
absorption on both the blue and red wings of the profiles and UU Aur is
notable only because it has significantly less absorption on the
blue-side of the profiles, relative to the other carbon stars. In this
paper, we present an analysis of the spectra and our interpretation,
based on all the available data, of these fascinating and complex line
profiles and their formation.
Title: Hubble Space Telescope Spectroscopy of the Carbon
Star TX PISCIUM
Authors: Carpenter, Kenneth G.; Robinson, Richard D.;
Johnson, Hollis R.; Eriksson, Kjell;
Gustafsson, Bengt; Pijpers, Frank P.;
Querci, Francois; Querci, Monique
Publication: Astrophysical Journal v.486, p.457
Publication Date: 09/1997
Origin: APJ
ApJ Keywords: STARS: CIRCUMSTELLAR MATTER, STARS: CARBON, STARS:
CHROMOSPHERES, STARS: INDIVIDUAL CONSTELLATION NAME:
TX PISCIUM, STARS: MASS LOSS, ULTRAVIOLET: STARS
Abstract Copyright: (c) 1997: The American Astronomical Society
DOI: 10.1086/304515
Bibliographic Code: 1997ApJ...486..457C
Abstract
Ultraviolet spectra obtained with the Hubble Space Telescope of the
carbon star TX Piscium (HR 9004) are presented, along with analysis
providing information on its outer atmosphere, including flow and
turbulent velocities, line formation mechanisms, and variations with
time. Both thermal (collisionally excited) and fluorescent emission from
the chromosphere of the star appear to be formed near the stellar rest
velocity, i.e., in a region below that in which the stellar wind is
accelerated. Absorption self-reversals in the Mg II emission confirm the
presence of an outflowing stellar wind at a mean velocity of about 9--10
km s-1. Circumstellar absorption features (Mn I and Fe I) overlying the
Mg II emission indicate a cool shell expanding at about 5--6 km s-1
relative to the photosphere. The widths (FWHM) of various emission lines
indicate that the chromospheric turbulence is at least 16 km s-1, but
that it may increase with altitude to as much as 34 km s-1. Three hours
of integration on the C II] lines are examined for any signs of
variability that might indicate the presence of shocks, but no
statistically significant variations are seen. A previous identification
(in spectra of UU Aur) of an emission line at 2807 Angstroms, seen only
in spectra of carbon stars, as belonging to Fe I multiplet UV45 pumped
by the C II] line at 2325 Angstroms is confirmed by the discovery of an
absorption feature corresponding exactly to the wavelength of the pumped
transition (Fe I UV13) near 2325 Angstroms. Lines from Fe II UV165,
previously seen in solar off-limb spectra and in Goddard High-Resolution
Spectrograph spectra of alpha Tau, are clearly present. The normally
much stronger Fe II UV32, 62, and 63 multiplets are seen but are weaker
relative to both the UV165 lines and the intercombination lines of C II]
and Si II] than in alpha Tau. The weakness of these Fe II lines is
indicated both by their absolute flux levels and by their narrow,
single-peaked profiles, which are in sharp contrast to the broad,
double-peaked profiles seen in oxygen-rich cool giant and supergiant
stars. The weakness of the Fe II lines and the presence of the Fe I 2807
Angstroms line suggest that the ionization fraction of iron (Fe II/Fe I)
is significantly lower in the outer atmospheres of carbon stars. Fluxes
in emission lines of Fe II and Mg II are >=2--3 times lower than in a
1984 IUE spectrum of TX Psc, confirming that the latter was obtained at
an epoch of unusual UV brightness for the star. The Mg II profiles are
heavily mutilated by overlying absorption, even more so than in 1984.
The TX Psc profiles are very similar to those seen in the carbon star TW
Hor but are dramatically different than those in another carbon star, UU
Aur, whose lines show violet wing emission out to much shorter
wavelengths than in the other two stars.
Title: The dynamical mass of the beat cepheid Y carinae and
stellar opacities.
Authors: Bohm-Vitense, E.; Evans, N. R.; Carpenter, K.;
Morgan, S.; Beck-Winchatz, B.; Robinson, R.
Publication: The Astronomical Journal, v. 114, p. 1176.
Publication Date: 09/1997
Origin: CARL
AJ/ApJ Keywords: CEPHEIDS, STARS: OSCILLATIONS, STARS: INDIVIDUAL: Y
CARINAE
DOI: 10.1086/118549
Bibliographic Code: 1997AJ....114.1176B
Abstract
The beat Cepheid, Y Carinae A, has a B9 V companion, Y Car B. The
primary period P0 of the Cepheid is 3.64 days and the
secondary, P1, is 2.56 days. Its period ratio
P1/P0 is thus 0.703. Y Car is the only beat
Cepheid known to be a binary and thus offers us the unique opportunity
to determine the dynamical mass for a beat Cepheid. We have determined
its mass by measuring the orbital velocity amplitude of the hot
companion Y Car B using the Goddard High-Resolution Spectrograph
(GHRS) with the G200M grating on the Hubble Space Telescope. When
combined with the ground-based orbital velocity amplitude of the
Cepheid and the mass of the companion, the implied mass of the
Cephieid is M=3.8±1.2Msun. With the Cepheid
luminosity given by the period-luminosity relation, this mass, taken
at face value, indicates excess mixing in the main sequence progenitor
corresponding to convective overshoot by about 0.9 pressure scale
height, however, the large error bars prevent a firm conclusion. As
shown by Simon the period ratio for beat Cepheids depends sensitively
on the opacities. For models calculated with Cox-Tabor opacities the
period ratios for beat Cepheids indicate masses between one and two
Msun. Models calculated with the new Livermore OPAL
opacities on the other hand indicate masses around 4 solar masses. The
good agreement of the beat mass with the dynamical mass, determined
here for Y Car, provides a confirmation that the OPAL opacities are a
significant improvement over the Cox-Tabor (1976) opacities.
Title: Observations of 3C273 with the Goddard High
Resolution Spectrograph on the Hubble Space
Telescope. II.
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.;
Boggess, A.; Carpenter, K. G.; Ebbets, D. C.;
Hutchings, J. B.; Jura, M.; Leckrone, D. S.;
Linsky, J. L.; Maran, S. P.; Savage, B. D.;
Smith, A. M.; Trafton, L. M.; Walter, F. M.;
Weymann, R. J.; Snow, M.; Randall, C. E.;
Tripp, T. M.; Ake, T. B.; Crenshaw, D. M.;
Bruhweiler, F. C.
Publication: Astronomical Journal v.114, p. 554-564 (1997)
Publication Date: 08/1997
Origin: CARL; AJ
AJ/ApJ Keywords: QUASARS: INDIVIDUAL: 3C 273, QUASARS: EMISSION LINES
DOI: 10.1086/118492
Bibliographic Code: 1997AJ....114..554B
Abstract
Observations of the quasar 3C 273 taken with the Goddard High Resolution
Spectrograph in November and December 1993 are presented here. We have
included both the fully-reduced spectra, and spectra combined with our
earlier (1991) observations. There are a total of 10 new medium
resolution exposures covering four wavelength regions: 1164-1201
Angstroms, 1214-1251 Angstroms, 1537-1573 Angstroms, and 1633-1670
Angstroms. We confirm the suggestion of Morris et al. (1991) that the
galactic Si IV lambda 1393 line is blended with an extragalactic lya
line by observing the lyb counterpart to this extragalactic line. We
obtain an improved upper limit on the C IV/H I ratio in these weak low
redshift lya absorption systems by coadding the corresponding C IV
spectral regions. Improved line profiles for the galactic C IV and N V
absorption are also presented and discussed. The improved measurements
lead to a downward revision of the galactic C IV column density, log N
(C IV) = 14.46+/- 0.04.
Title: The Mass of the Classical Cepheid V350 SGR
Authors: Evans, N. R.; Bohm-Vitense, E.; Carpenter, K.;
Beck-Winchatz, B.; Robinson, R.
Publication: Publications of the Astronomical Society of the
Pacific, v.109, p.789-795
Publication Date: 07/1997
Origin: PASP
PASP/ApJ Keywords: CEPHEIDS, STARS: EVOLUTION
Abstract Copyright: (c) 1997: Astronomical Society of the Pacific
DOI: 10.1086/133945
Bibliographic Code: 1997PASP..109..789E
Abstract
Two medium resolution spectra of the hot companion of the Cepheid V350
Sgr have been obtained with the Goddard High Resolution Spectrograph
aboard the Hubble Space Telescope. Comparison of these spectra (in the
wavelength range 1840 to 1880 \AA) with the spectrum of $\alpha$ Lyr
shows that V350 Sgr B has a projected rotation velocity which may be as
high as 150 km sec$^{-1}$. The velocity difference between the spectra
of V350 Sgr B at two orbital phases is measured to be -23.1 $\pm$ 3.8 km
sec$^{-1}$. The error is dominated by the aperture centering. When
combined with the orbital velocity variation of the Cepheid derived from
the ground-based orbit and the mass of the companion deduced from IUE
spectra, the mass of the Cepheid is found to be 5.2 $\pm$ 0.9 M$\sun$.
The observed mass--luminosity combination of V350 Sgr A is a good match
to recent evolutionary calculations which use moderate convective
overshoot near the main sequence, however, the blue loops do not extend
to temperatures as hot as the Cepheid. (SECTION: Stars)
Title: The outer atmospheres of cool, low gravity stars as
revealed by HST
Authors: Carpenter, Kenneth G.
Affiliation: AA(NASA Goddard Space Flight Center)
Publication: Baltic Astronomy, vol. 6,, p. 73
Publication Date: 07/1997
Category: Astrophysics
Origin: STI
NASA/STI Keywords: COOL STARS, STELLAR ATMOSPHERES, HUBBLE SPACE
TELESCOPE, STELLAR GRAVITATION, STELLAR WINDS,
PLASMA ACCELERATION, SPECTROGRAPHS, HIGH RESOLUTION,
GIANT STARS, SUPERGIANT STARS, CHROMOSPHERE, PLASMA
TURBULENCE, STELLAR SPECTRA
Bibliographic Code: 1997BaltA...6...73C
Abstract
We have used the Goddard High Resolution Spectrograph (GHRS) on the HST
to measure the macroturbulent and flow velocities, the acceleration of
winds, and the amount of hot (transition-region) plasma in the outer
atmospheres of Carbon and K-M Giant/Supergiant stars. We see the
acceleration of the stellar winds in the chromospheres of several of
these stars from initial velocities of 3-9 km/s to upper velocities of
15-25 km/s and measured chromospheric macroturbulences ranging from
approximately 25 to 35 km/s. We have found in the in the nowcoronal
giant Alpha Tau weak C IV emission indicative of hot transition-region
plasma, many new fluorescent lines of Fe II, and fluorescent molecular
hydrogen emission, and Ca II recombination lines seen for the first time
in a giant star.
Title: GHRS Observations of Cool, Low-Gravity Stars. III.
Plasma Flows and Turbulence in the Outer Atmosphere
of alpha Orionis (M2 Iab)
Authors: Carpenter, Kenneth G.; Robinson, Richard D.
Publication: Astrophysical Journal v.479, p.970
Publication Date: 04/1997
Origin: APJ
ApJ Keywords: STARS: CHROMOSPHERES, ULTRAVIOLET: STARS, STARS:
INDIVIDUAL CONSTELLATION NAME: ALPHA ORIONIS, STARS:
LATE-TYPE, TURBULENCE
Abstract Copyright: (c) 1997: The American Astronomical Society
DOI: 10.1086/303888
Bibliographic Code: 1997ApJ...479..970C
Abstract
We present the results of a Goddard High Resolution Spectrograph (GHRS)
study of flow and turbulent velocities in the outer atmosphere of the M2
Iab supergiant alpha Ori. Ions with observed chromospheric emission
features include C I, C II, Si I, Si II, O I, Co II, Al II, Mg II, Cr
II, Fe I, and Fe II, while the photospheric absorption spectrum is
dominated by Fe I. The widths of optically thin lines of C II], Si II],
Co II, and Fe II indicate an average chromospheric turbulent velocity
(Doppler FWHM) in the range of 31--35 km s-1, which is substantially
above the expected chromospheric sound velocity. The shape of the C II]
profiles indicates that this turbulence is probably anisotropically
distributed, with velocities preferentially directed along and/or
perpendicular to the radial direction. The radial velocity of near-UV Fe
I photospheric absorption lines averaged 18 km s-1, somewhat smaller
than the systemic RV of alpha Ori itself (21 km s-1) and significantly
smaller than the RV of the optical Fe I lines (23 km s-1) at the time of
the HST observations. The various components of the chromospheric
emission lines had radial velocities in the range 7--36 km s-1. The
emission wings for most of the ionic species averaged ~20 km s-1, i.e.,
they were nominally at rest with regard to the star. The central
absorption features in these lines, however, showed lower velocities,
averaging ~16 km s-1. The radial velocity of the central reversals in
the stronger lines was also found to be correlated with the opacity of
the lines, changing from ~20 km s-1 for the lower opacity lines to ~14
km s-1 for the higher opacity lines. This implies that we are directly
viewing the acceleration of the stellar wind in the chromosphere from
rest to about 7 km s-1. Contrary to the results reported earlier by
Carpenter (1984) on the basis of IUE data, there is no indication of a
deceleration of the wind at large distances from the star.
Title: A Comparison of Magnetic Hysteresis Models Under
High Frequency Excitation
Authors: Carpenter, Kenneth H.
Affiliation: Department of Electrical and Computer Engineering,
Kansas State University, Manhattan, KS 66506
Publication: American Physical Society, Annual March Meeting,
March 17-21, 1997, abstract \#J19.10
Publication Date: 03/1997
Origin: APS
Bibliographic Code: 1997APS..MAR.J1910C
Abstract
Modeling of magnetic hysteresis can be approached from a variety of
viewpoints. Most models are successful in producing realistic low
frequency hysteresis loops, but differ in ability to follow material
magnetization dynamically. Model parameters may be chosen to give
reasonable results for single frequency sinusoidal excitations. Some
models may also be tuned to give reasonable results for excitation by
high speed pulses. To illustrate the limitations of the various
approaches, several models will be compared for different frequencies of
sinusoidal and pulse excitation. The divergence of the results for
excitations removed from the ones for which the models are tuned suggest
possible approaches to follow for wide bandwidth simulations.
Title: The Mass of the Classical Cepheid S MUSCAE
Authors: Boehm-Vitense, Erika; Remage Evans, Nancy;
Carpenter, Kenneth; Beck-Winchatz, Bernhard;
Robinson, Richard
Publication: Astrophysical Journal v.477, p.916
Publication Date: 03/1997
Origin: APJ
ApJ Keywords: STARS: BINARIES: VISUAL, STARS: VARIABLES: CEPHEIDS,
STARS: EVOLUTION, STARS: FUNDAMENTAL PARAMETERS,
STARS: INDIVIDUAL CONSTELLATION NAME: S MUSCAE,
STARS: INTERIORS
Abstract Copyright: (c) 1997: The American Astronomical Society
DOI: 10.1086/303725
Bibliographic Code: 1997ApJ...477..916B
Abstract
A good determination of the mass-luminosity relation for evolved stars
on blue loops can determine the degree of excess mixing in the interiors
of their main-sequence companions. In this study we determine the
dynamical mass of the Cepheid binary S Muscae. This can be combined with
its known luminosity and be fitted on evolutionary tracks to determine
the amount of mixing in the main-sequence progenitor. Using the Goddard
High Resolution Spectrograph on the Hubble Space Telescope we have
measured the orbital radial velocity changes for the companion of the
Cepheid S Mus. Spectra taken at minimum and maximum orbital velocities
were cross-correlated. The velocity difference was measured to be 30.6
+/- 0.4 km s-1. The difference for the orbital velocities of the Cepheid
for the same phases was determined to be 26.9 km s-1 +/- 0.4 km s-1.
This gives a velocity ratio of 1.14 +/- 0.02, which gives us the mass
ratio for the companions. Adding possible centering errors of the target
in the entrance apertures the error limit would be increased to +/-0.06.
The derived spectral types of the companion S Mus B range from B3 V to
B5 V depending on the criterion used to determine it, with an average
spectral type B3.8 V. Using the average spectral type and the
main-sequence mass-spectral type relation from Andersen & Harmanec
we find for S Mus B a mass of 5.2 +/- 0.2 Mo. With the newly
determined mass ratio the mass for the Cepheid S Mus A comes out to be
5.9^{+0.7}_{-0.6} Mo. Taking the mass of 5.9 Mo at face value
and adopting the absolute visual magnitude of Mv = -4.29 (log L/Lo
= 3.62) for the Cepheid S Mus this indicates mixing in its main-sequence
progenitor slightly in excess of the one assumed for the Maeder and
Meynet evolutionary tracks. The present uncertainties in mass and
luminosity prevent, however, a firm conclusion about the exact degree of
mixing.
Title: Winds and Mass-Loss from Evolved, Low-Gravity Cool
Stars
Authors: Carpenter, K.; Robinson, R.
Affiliation: AA(Laboratory for Astronomy and Solar Physics,
AB(Astronomy Programs, Computer Sciences
Corporation, @NASA-GSFC,
Publication: Stellar Evolution in Real Time, 23rd meeting of the
IAU, Joint Discussion 8, 22-23 August 1997, Kyoto,
Japan, meeting abstract.
Publication Date: 00/1997
Origin: AUTHOR
Bibliographic Code: 1997IAUJD...8E..28C
Abstract
The character of the winds and the amount of mass-loss from stars during
the red giant and supergiant stage of evolution are critical to the
progression of that evolution. We therefore summarize here the results
of a series of programs utilizing the Goddard High Resolution
Spectrograph (GHRS) on the Hubble Space Telescope (HST) to study the
winds and mass-loss from the surface of evolved, low-gravity cool stars.
We discuss the structure of the chromospheres in which the base of these
stellar winds lie, the velocity of the wind and its acceleration with
height, and what these spectra tell us about the mass-loss from these
stars. Because of its relevance to this Joint Discussion, we will also
discuss in some detail what we have learned about real-time variability
of these phenomena and the implied somewhat erratic nature of the
mass-loss process in at least some of these stars.
Title: New Results on Cepheid Masses
Authors: Evans, N. R.; Bohm-Vitense, E.; Carpenter, K.;
Robinson, R.; Beck-Winchatz, B.
Affiliation: AA(SAO), AB(U. Washington), AC(NASA/GSFC),
AD(NASA/GSFC), AE(U. Washington)
Publication: American Astronomical Society, 189th AAS Meeting,
\#96.08; Bulletin of the American Astronomical
Society, Vol. 28, p.1399
Publication Date: 12/1996
Origin: AAS
Abstract Copyright: (c) 1996: American Astronomical Society
Bibliographic Code: 1996AAS...189.9608E
Abstract
Masses for Cepheid variable stars can be measured by combining the
orbital velocity amplitude for the Cepheid (from a ground-based orbit)
with the orbital velocity amplitude of a hot main sequence companion
(observed in the ultraviolet from satellites such as IUE and HST) and
the mass of the companion (inferred from from the ultraviolet energy
distribution). Observations of 5 binary systems are now completed or in
progress with the Goddard High Resolution Spectrograph on the Hubble
Space Telescope. Recently completed observations of U Aql lead to a mass
of 5.1 +/- 1.1 Msun. We will discuss the results for S Mus, V350 Sgr, U
Aql, and Y Car, and the constraints they place on stellar evolution
calculations. As would be expected, some of the B companions have high
rotational velocities, decreasing the accuracy with which their orbital
velocities can be measured. The preliminary conclusion from the 4 HST
targets and SU Cyg (mass from IUE observations) is that a weighted mean
indicates no convective overshoot but the mode (which reflects the HST
results better) agrees with the modest overshoot used in the Geneva
evolutionary calculations. Financial Support was provided by a NASA
grant GO-4541-01 to EB--V and GO-4541.02 to KGC, a grant from the
Natural Sciences and Engineering Council, Canada to NRE, from the AXAF
Science Center NASA Contract NAS8-39073.
Title: Fishing in the Coronal Graveyard
Authors: Ayres, T. R.; Brown, A.; Harper, G. M.;
Bennett, P. D.; Linsky, J. L.; Carpenter, K. G.;
Robinson, R. D.
Affiliation: AA(CASA), AB(CASA), AC(CASA), AD(CASA), AE(JILA),
AF(GSFC), AG(CSC)
Publication: American Astronomical Society, 189th AAS Meeting,
\#78.15; Bulletin of the American Astronomical
Society, Vol. 28, p.1379
Publication Date: 12/1996
Origin: AAS
Abstract Copyright: (c) 1996: American Astronomical Society
Bibliographic Code: 1996AAS...189.7815A
Abstract
Hot coronae (T ~ 10(6) K) are thought to be rare among single giant
stars to the right of the ``Linsky--Haisch dividing line'' near K0 in
the H--R diagram. K and M giants are such slow rotators that absence of
dynamo generated magnetic activity would be natural. Nevertheless, gamma
Dra (K5 III) unexpectedly was detected in FUV coronal proxies---hot
lines Si IV lambda 1393 and C IV lambda 1548---by HST /GHRS during
Science Verification, and subsequently was discovered as a faint X-ray
source in a deep ROSAT /PSPC pointing. Is gamma Dra anomalous, or is the
lack of coronal detections among the K giants simply a matter of
insufficient sensitivity? We have used the GHRS low resolution mode to
search for additional examples of hot lines among inactive single red
giants. Si IV provides a clean diagnostic of subcoronal material because
it falls near the peak sensitivity of the G140L mode and does not suffer
from abundance depletions that can affect C IV in red giants. X-ray/Si
IV ratios are such that HST can reach to much fainter limiting
``coronal'' magnitudes than even very deep ROSAT pointings. In every
target so far examined, we find weak---but statistically
significant---Si IV emission. These include: the ancient red giant
Arcturus (alpha Boo: K1 III), recorded at the end of Cycle 5; and
epsilon Crv (K2.5 III) and epsilon Sco (K2 III) observed in Cycle 6.
X-ray/Si IV ratios of red giants (for which measurements, or upper
limits, of both diagnostics are available) fall on a uniform track,
extending downward from active K0 ``Clump'' giants like beta Ceti all
the way to Arcturus itself, in the depths of the ``coronal graveyard.''
The systematic behavior argues that magnetic dynamo action continues
even when long term angular momentum loss has slowed the stellar spin to
a crawl. This work was supported by grant GO-06066.01-94A from STScI.
Title: Observing Stellar Coronae with the Goddard High
Resolution Spectrograph. II. The RS CVn Binary
System HR 1099
Authors: Robinson, R. D.; Airapetian, V. S.; Maran, S. P.;
Carpenter, K. G.
Publication: Astrophysical Journal v.469, p.872
Publication Date: 10/1996
Origin: APJ
ApJ Keywords: STARS: CORONAE, STARS: INDIVIDUAL BRIGHT STAR
NUMBER: HR 1099, STARS: CHROMOSPHERES, ULTRAVIOLET:
STARS
DOI: 10.1086/177834
Bibliographic Code: 1996ApJ...469..872R
Abstract
We report time series observations of the RS CVn star HR 1099 taken
with the Goddard High Resolution Spectrograph onboard the Hubble Space
Telescope. The data cover a wavelength range from 1342 to 1375 Å
and show a measurable continuum, as well as emission lines of O I, C
I, CII, Fe II, O V, and Fe XXI. The chromospheric and transition
region features are seen only in the active K1 IV component of the
binary system, while the Fe XXI (1O7 K) flux may come from
both components, with the active component having the stronger
flux. There is no indication of Fe MI emission, formed at 1.3 x
106 K. The width of the Fe XXI profile indicates that the
corona of the primary is unlikely to extend to heights greater than
2.3R*, while other indicators suggest that the
average loops are really much smaller, having a length of ~3 x
1010 cm with an electron density on the order of
1010 cm-3. Some evidence for atmospheric
turbulence is detected in all of the observed emission lines. This
turbulence initially increases with height, going from less than 30 km
s-1 in the chromosphere to as much as 150 km s-1
in the transition region. The turbulence then decreases in the corona,
where velocities of less than 65 km s-1 are
indicated. Theoretical fits to the O V profile also suggest that this
turbulence is anisotropically distributed, with motions directed
primarily along or perpendicular to the radial direction. While
admitting the possibility that the atmosphere is heated by microflare
events, we examine an alternative heating process that involves the
damping of MHD turbulence, which might be generated by nonlinear
Alfvén waves or by shocks. Simple calculations indicate that the
observed turbulence is sufficient to account for the transition region
and coronal heating.
Title: UV Emission from the Atmosphere of Jupiter After the
S-Impact of Comet SL9
Authors: Carpenter, K. G.; McGrath, M. A.; Yelle, R. V.
Affiliation: AA(LASP-NASA/GSFC), AB(STScI), AC(Boston U.)
Publication: American Astronomical Society, DPS meeting \#28,
\#22.47; Bulletin of the American Astronomical
Society, Vol. 28, p.1150
Publication Date: 09/1996
Origin: AAS
Abstract Copyright: (c) 1996: American Astronomical Society
Bibliographic Code: 1996DPS....28.2247C
Abstract
The Hubble Space Telescope Faint Object Spectrograph was used to obtain
a UV spectrum of the impact site of the S-fragment of comet SL9
approximately 45 minutes after the entry of the fragment into the
atmosphere of Jupiter. This spectrum contains ultraviolet emission lines
of neutral and ionized metals, including Mg I, Mg II, Fe I, Fe II, and
Si I. Initial analyses of these data were presented by Noll et al.
(1995, Science, 267, 1307) based on a pure solar resonance fluoresence
synthetic spectrum and assuming collisional excitation at 1000 K, and by
Carpenter et al. (DPS, Oct. 1995) who added non-resonance fluorescence
and examined the possibility that some of the emission was caused by
thermal excitation of metastable levels during the fireball and
splashback phases of the impact. Since these line formation models do
not fully account for the observed relative and absolute line fluxes, we
have enhanced our model to include non-LTE effects, heating of the
atmosphere due to infalling gas and dust, and the effects of multiple
scatterings of photons as they attempt to exit the atmosphere of Jupiter
at frequencies within optically thick lines. We compare the synthetic
spectrum produced with this model to the observed spectrum and discuss
the physical conditions and elemental abundances inferred from this
comparison.
Title: High Signal-to-Noise Ratio Observations of Weak
Interstellar Absorption Lines Towards XI Ophiuchi
With the Goddard High-Resolution Spectrograph Aboard
the Hubble Space Telescope
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.;
Boggess, A.; Carpenter, K. G.; Ebbets, D. C.;
Hutchings, J. B.; Jura, M.; Leckrone, D. S.;
Linsky, J. L.; Maran, S. P.; Savage, B. D.;
Smith, A. M.; Trafton, L. M.; Walter, F. M.;
Weymann, R. J.; Hogen, R.; Snow, M.; Cardelli, J. A.;
Ake, T. B.; Bruhweiler, F.
Publication: Astronomical Journal v.112, p.1128
Publication Date: 09/1996
Origin: AJ
AJ/ApJ Keywords: STARS: INDIVIDUAL: XI OPHIUCHI, ULTRAVIOLET:
INTERSTELLAR
DOI: 10.1086/118084
Bibliographic Code: 1996AJ....112.1128B
Abstract
We present an atlas and tabulation of weak interstellar absorption
lines in the ultraviolet spectrum of zeta Ophiuchi in four selected
wavelength regions observed with the Goddard High Resolution
Spectrograph aboard the Hubble Space Telescope. The signal-to-noise
ratio ranges from 150 to nearly 400, and the spectral resolving power
exceeds 20 000, allowing 2sigma detections of features as weak as
Wlambda=0.8 mÅ. We report positive measurements of two lines
of OH, and weak detections of P I, Tl II, and N V. Upper limits of
Wlambda<1 mÅ are found for the molecules H2O,
HCl, SiO, NO+, and CH2. Similar limits are found for heavy
elements Te II, Co II, and Sb II. Three lines are present in our
spectrum for which we have no identifications. They are found at
wavelengths of lambda=1229.84, 1313.98, and 1314.23
Å. However, none of the features reported by previous authors as
unidentified absorption lines in the wavelength regions we have
observed are present in our data.
Title: Probing the Chromospheric Structure of Alpha Tau
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#6722
Publication Date: 07/1996
Origin: HST
Keywords: HST Proposal ID \#6722 COOL STARS
Bibliographic Code: 1996hst..prop.6722C
Abstract
Fluorescent H_2 lines {excited by Hydrogen LyAlpha} and Ca II lines
formed by recombination after photoionization by H LyAlpha were recently
seen in GHRS spectra of the K5 III star Alpha Tau. This is the first
time these lines have been seen in a giant star. The presence of these
lines provides an opportunity to probe the structure of the upper
chromosphere {Ca II} and of the low chromosphere/temperature minimum
region {H_2} in this star and to test existing and new theoretical
models of the outer atmosphere of Alpha Tau. In addition, the H_2 lines
allow us to probe cooler regions than possible using the standard atomic
emission line diagnostics and thus enable us to test the hypothesis of
Wiedemann et al. {1994 ApJ 423, 806} that the atmosphere of cool giants
are thermally bifurcated in the region above the photosphere. We propose
to obtain, during Cycle 6, observations of the full set of Ca II and H_2
lines needed to perform these analysis and tests and to use these data
to create new models of the chromosphere of Alpha Tau.
Title: Hubble Space Telescope Observations of the Seyfert
Galaxy NGC 3783: Discovery of Variable C IV
Absorption
Authors: Maran, Stephen P.; Crenshaw, D. Michael;
Mushotzky, Richard F.; Reichert, Gail A.;
Carpenter, Kenneth G.; Smith, Andrew M.;
Hutchings, John B.; Weymann, Ray J.
Publication: Astrophysical Journal v.465, p.733
Publication Date: 07/1996
Origin: APJ; NED
ApJ Keywords: GALAXIES: INDIVIDUAL NGC NUMBER: NGC 3783, GALAXIES:
SEYFERT, ULTRAVIOLET: GALAXIES
DOI: 10.1086/177457
Bibliographic Code: 1996ApJ...465..733M
Abstract
We have discovered variable absorption lines in HST spectra of the
Seyfert 1 galaxy NGC 3783. C IV lambdalambda1548.2, 1550.8
absorption is present in an FOS spectrum on 1992 July 27 and a GHRS
spectrum on 1994 January 16 at a radial velocity of -450 km s^-1^
relative to the emission-line peak, but there is no evidence for
absorption in a GHRS spectrum on 1993 February 5. A GHRS spectrum on
1993 February 21, obtained just 16 days after the spectrum with no
detectable C IV absorption, shows strong N V lambdalambda1238.8,
1242.8 absorption lines, also at a radial velocity of -450 km s^-1^. The
observations place constraints on the two types of models for
absorption-line variability: bulk motion into the line of sight, and
variable ionization of gas already in the line of sight.
Title: Dinosaur Eggs and Babies
Authors: Carpenter, Kenneth; Hirsch, Karl F.; Horner, John R.
Affiliation: AA(Denver Museum of Natural History),AB(Denver
Museum of Natural History),AC(Museum of the Rockies)
Publication: Dinosaur Eggs and Babies, Edited by Kenneth
Carpenter and Karl F. Hirsch and John R. Horner, pp.
448. ISBN 0521567238. Cambridge, UK: Cambridge
University Press, January 1996.
Publication Date: 01/1996
Origin: CUP
Bibliographic Code: 1996deb..book.....C
Abstract
In the last couple of decades the study of dinosaur eggs and babies has
proved to be one of the most exciting and profitable areas of dinosaur
research. This is the first book solely devoted to this topic and
reviews, in scientific detail, our present state of knowledge about this
exciting area of palaeontology. Chapters in the book discuss all aspects
of the science including the occurrence of eggs, nests and baby
skeletons, descriptive osteology of juvenile skeletons, comparative
histology of juvenile bone, analyses of eggs and egg shells,
palaeoenvironments of nesting sites, nesting behaviour and developmental
growth of baby dinosaurs. The volume will be an invaluable addition to
the book collections of vertebrate palaeontologists and their graduate
students.
Title: HST Studies of Carbon and K-M Giant/Supergiant Stars
Authors: Carpenter, K. G.; Robinson, R. D.
Publication: Science with the Hubble Space Telescope - II.
Proceedings of a workshop held in Paris, France,
December 4-8, 1995. Edited by Piero Benvenuti, F.D.
Macchetto, and Ethan J. Schreier. Baltimore, MD:
Space Telescope Science Institute (STScI), 1996.,
p.418
Publication Date: 00/1996
Origin: ADS
Bibliographic Code: 1996swhs.conf..418C
Abstract
Not Available
Title: Rapid UV spectroscopy of flares on YZ CMi
Authors: Robinson, R. D.; Woodgate, B. E.; Carpenter, K. G.
Publication: Cool stars; stellar systems; and the sun: 9 :
Astronomical Society of the Pacific Conference
Series, volume 109; Proceedings of the 9th Cambridge
workshop; held 3-6 October 1995 in Florence; Italy;
San Francisco: Astronomical Society of the Pacific
(ASP); |c1996; edited by Roberto Pallavicini and
Andrea K. Dupree, p.285
Publication Date: 00/1996
Origin: ADS
Bibliographic Code: 1996ASPC..109..285R
Abstract
Not Available
Title: Identification and analysis of UV emission lines
observed near 1550 Angstroms in the spectrum of
alpha Tau obtained with the GHRS
Authors: McMurry, A. D.; Jordan, C.; Rowe, A. K.;
Carpenter, K. G.; Robinson, R. D.
Publication: Cool stars; stellar systems; and the sun: 9 :
Astronomical Society of the Pacific Conference
Series, volume 109; Proceedings of the 9th Cambridge
workshop; held 3-6 October 1995 in Florence; Italy;
San Francisco: Astronomical Society of the Pacific
(ASP); |c1996; edited by Roberto Pallavicini and
Andrea K. Dupree, p.271
Publication Date: 00/1996
Origin: ADS
Bibliographic Code: 1996ASPC..109..271M
Abstract
Not Available
Title: Examining the coronal heating on the RS CVn binary
HR 1099
Authors: Airapetian, V.; Robinson, R. D.; Maran, S. P.;
Carpenter, K. G.
Publication: Cool stars; stellar systems; and the sun: 9 :
Astronomical Society of the Pacific Conference
Series, volume 109; Proceedings of the 9th Cambridge
workshop; held 3-6 October 1995 in Florence; Italy;
San Francisco: Astronomical Society of the Pacific
(ASP); |c1996; edited by Roberto Pallavicini and
Andrea K. Dupree, p.249
Publication Date: 00/1996
Origin: ADS
Bibliographic Code: 1996ASPC..109..249A
Abstract
Not Available
Title: Empirical constraints on wind flows and turbulence
from HST observations of cool giants and supergiants
Authors: Carpenter, K. G.
Publication: Cool stars; stellar systems; and the sun: 9 :
Astronomical Society of the Pacific Conference
Series, volume 109; Proceedings of the 9th Cambridge
workshop; held 3-6 October 1995 in Florence; Italy;
San Francisco: Astronomical Society of the Pacific
(ASP); |c1996; edited by Roberto Pallavicini and
Andrea K. Dupree, p.243
Publication Date: 00/1996
Origin: ADS
Bibliographic Code: 1996ASPC..109..243C
Abstract
Not Available
Title: The Transition Region, Corona, Chromosphere, and
Wind of the K5 Giant gamma Draconis
Authors: Brown, A.; Carpenter, K. G.; Robinson, R. D.;
Harper, G. M.; Deeney, B. D.; Ayres, T. R.
Affiliation: AA(CASA, U. of Colorado), AB(NASA/GSFC),
AC(CSC/GSFC), AD(JILA, U. of Colorado), AE(CASA, U.
of Colorado), AF(CASA, U. of Colorado)
Publication: American Astronomical Society, 187th AAS Meeting,
\#103.03; Bulletin of the American Astronomical
Society, Vol. 27, p.1430
Publication Date: 12/1995
Origin: AAS
Abstract Copyright: (c) 1995: American Astronomical Society
Bibliographic Code: 1995AAS...18710303B
Abstract
Gamma Draconis (K5 III) is the first single, normal late K giant located
on the red side of the coronal ``dividing line'' known to show
conclusive evidence for both hot ( ~ 10(5) K) transition \ region (TR)
and coronal (> 10(6) K) plasma. We present HST GHRS ultraviolet
spectra of gamma Dra obtained on 1995 July 20 and 1991 April 6/18. These
observations include spectra obtained at low, medium, and echelle
resolution that provide a full set of chromospheric and TR emission line
fluxes and profiles. These are combined with ROSAT PSPC observations to
measure the TR and coronal properties, such as emission measure
distribution, electron density, and nonthermal velocity fields, of this
star. The high temperature emissions of gamma Dra are compared to those
of a sample of hybrid-chromosphere bright giants and supergiants. This
work is supported by Space Telescope Science Institute grant
GO-06068.01-94A and NASA grants NAG5-1792 and NAGW-4529 to the
University of Colorado.
Title: The Mass of the Cepheid S Muscae.
Authors: Bohm-Vitense, E.; Evans, N. R.; Beck-Winchatz, B.;
Carpenter, K.; Robinson, R.
Affiliation: AA(UW), AB(CFA), AC(UW), AD(GSFC), AE(GSFC)
Publication: American Astronomical Society, 187th AAS Meeting,
\#102.05; Bulletin of the American Astronomical
Society, Vol. 27, p.1428
Publication Date: 12/1995
Origin: AAS
Abstract Copyright: (c) 1995: American Astronomical Society
Bibliographic Code: 1995AAS...18710205B
Abstract
Using the Goddard High Resolution Spectrograph on the Hubble Space
Telescope we have measured the orbital radial velocity changes for the
companion of the Cepheid S Muscae. The observations were done at minimum
and maximum orbital velocities. The two spectra were cross-correlated.
The velocity difference was measured to be 30.6 +/- 0.4 km/s. The
difference for the orbital velocities of the Cepheid for the same phases
was determined to be 26.9 +/-0.4 km/s. This gives a mass ratio of 1.14
+/-0.06. For a spectral type between B3.5 V and B5 V for the companion S
Mus B its mass is 5.0 +/- 0.3 M(sun). With the mass ratio of 1.14 the
mass of the Cepheid, with a period of 9.6 days, comes out to be 5.7 +/-
0.4 solar masses. This compares with a pulsational mass of 5.5 solar
masses. Taking the 5.7 solar masses for the Cepheid at face value its
absolute visual magnitude of M(V)=-4.29 indicates a high degree of
excess interior mixing in its main sequence progenitor corresponding to
convective overshoot by one pressure scale height. Even for the upper
mass limit the excess mixing has to correspond to convective overshoot
by 1/2 pressure scale height.
Title: The Astrophysical Laboratory RR Tel: Observations
Authors: Harper, G. M.; Brown, A.; Robinson, R. D.;
Jordan, C.; Carpenter, K. G.; Shore, S. N.
Affiliation: AA(U. of Colorado at Boulder), AB(U. of Colorado at
Boulder), AC(CSC/GSFC), AD(Theoretical Physics, U.
of Oxford, U.K.), AE(NASA/GSFC/LASP), AF(Physics
Dept., Indiana U. South Bend)
Publication: American Astronomical Society, 187th AAS Meeting,
\#19.10; Bulletin of the American Astronomical
Society, Vol. 27, p.1313
Publication Date: 12/1995
Origin: AAS
Abstract Copyright: (c) 1995: American Astronomical Society
Bibliographic Code: 1995AAS...187.1910H
Abstract
The rich emission line spectrum of the bright symbiotic nova RR Tel
provides one of the best laboratories for determining empirical values
of atomic parameters, including branching ratios, Einstein A-values and
electron collision strengths. In addition to providing atomic parameters
not measurable in the laboratory, the observations also test recent
theoretical calculations of these parameters. In July 1995 we obtained
high quality low and medium resolution, large aperture spectra of RR Tel
using the Goddard High Resolution Spectrograph (GHRS) on board the
Hubble Space Telescope. These spectra sample wavelengths from 1100
Angstroms to 2680 Angstroms and contain numerous lines of astrophysical
interest which will be used to derive empirical atomic data (e.g.
branching ratios in C II], N III], O III] and O IV]) as well as lines
from which the local temperature and density can be determined. The GHRS
spectra have greater dynamic range and lower background noise than
available high resolution IUE data, permitting detailed evaluation of
spectral diagnostics even for the weak emission features from some
intercombination and forbidden transitions. In this paper we show
examples of the spectra, discuss the atomic transitions for which atomic
data will be derived and describe the methods used in determining these
parameters. RR Tel and AG Peg, both of which have been observed with the
GHRS, are fundamental for studying time variability of spectra of a
symbiotic nova and the GHRS observations will be compared with previous
IUE results to investigate this variability. We will also discuss the
observed flows and turbulence found from the line profiles as well as
the shape of the UV continuum. Support for this work was provided by
NASA through grant number GO-05863.01-94A from the Space Telescope
Science Institute, which is operated by the Association of Universities
for research in Astronomy, Inc., under NASA contract NAS5-26555.
Title: A Search for Microflaring Activity on dMe Flare
Stars. I. Observations of the dM8e Star CN Leonis
Authors: Robinson, R. D.; Carpenter, K. G.; Percival, J. W.;
Bookbinder, J. A.
Publication: Astrophysical Journal v.451, p.795
Publication Date: 10/1995
Origin: APJ; KNUDSEN
ApJ Keywords: STARS: ACTIVITY, STARS: FLARE, STARS: INDIVIDUAL
CONSTELLATION NAME: CN LEONIS, ULTRAVIOLET: STARS
DOI: 10.1086/176266
Bibliographic Code: 1995ApJ...451..795R
Abstract
Microflares are frequent, short-duration, energetically weak
disturbances occurring in the nonradiatively heated regions of the Sun
and other magnetically active stars. They are thought to be the
low-energy extension of flares commonly seen on active dMe stars and
may be a major source of heating the chromosphere and corona of cool
stars in general. In this paper we describe rapid time sequence UV
photometry of the dMe star CN Leo taken with the High Speed Photometer
(HSP) aboard the Hubble Space Telescope (HST). The filter was centered
at 240 nm, near wavelengths at which flares are expected to have
maximum intensity and the stellar background is small. During 2 hr of
on-source observing, a total of 32 flarelike events were detected,
with integrated counts ranging from 12 to more than 14,000. In most
cases the events had integrated energy ranging between 1027
and 1028 ergs and can be classified as microflares. A
considerable fine structure was seen in these events, with substantial
variations sometimes occurring on timescales of less than 1 s. The
occurrence rates for the smaller events showed a power-law
distribution, with a slope comparable to that seen for larger events
observed from the ground. Extrapolating the occurrence rate relation
to nanoflare energies indicates a predicted count rate that is
significantly smaller than that observed, suggesting that the
nanoflares have a different energy distribution than the larger
events.
Title: The Goddard High Resolution Spectrograph: In-Orbit
Performance
Authors: Heap, S. R.; Brandt, J. C.; Randall, C. E.;
Carpenter, K. G.; Leckrone, D. S.; Maran, S. P.;
Smith, A. M.; Beaver, E. A.; Boggess, A.;
Ebbets, D. C.; Garner, H. W.; Hutchings, J. B.;
Jura, M.; Linsky, J. L.; Savage, B. D.;
Cardelli, J. A.; Trafton, L. M.; Walter, F. M.;
Weymann, R. J.; Ake, T. B.; Crenshaw, D. M.;
Malamuth, E. M.; Robinson, R. D.; Sandoval, J. L.;
Shore, S. N.; Wahlgren, G. M.; Bruhweiler, F.;
Lindler, D. J.; Gilliland, R. L.; Hulbert, S. J.;
Soderblom, D. R.
Publication: Publications of the Astronomical Society of the
Pacific, v.107, p.871
Publication Date: 09/1995
Origin: PASP; KNUDSEN
PASP/ApJ Keywords: INSTRUMENTATION: SPECTROGRAPHS
Abstract Copyright: (c) 1995: Astronomical Society of the Pacific
DOI: 10.1086/133635
Bibliographic Code: 1995PASP..107..871H
Abstract
The in-orbit performance of the Goddard High Resolution Spectrograph
onboard the Hubble Space Telescope (HST) is presented. This report
covers the pre-COSTAR period, when instrument performance was limited by
the effects of spherical aberration of the telescope's primary mirror.
The digicon detectors provide a linear response to count rates spanning
over six orders of magnitude, ranging from the normal background flux of
0.01 counts diode ^-1 s^-1 to values larger than 10^4 counts diode^-1
s^-1. Scattered light from the first-order gratings is small and can be
removed by standard background subtraction techniques. Scattered light
in the echelle mode is more complex in origin, but it also can be
accurately removed. Data have been obtained over a wavelength range from
below 1100 A to 3300 A, at spectral resolutions as high as R =
lambda/delta-lambda = 90,000. The wavelength scale is influenced by
spectrograph temperature, outgassing of the optical bench, and
interaction of the magnetic field within the detector with the earth's
magnetic field. Models of these effects lead to a default wavelength
scale with an accuracy better than 1 diode, corresponding to 3 km s^-1
in the echelle mode. With care, the wavelength scale can be determined
to an accuracy of 0.2 diodes. Calibration of the instrument sensitivity
functions is tied into the HST flux calibration through observations of
spectrophotometric standard stars. The measurements of vignetting and
the echelle blaze function provide relative photometric precision to
about 5% or better. The effects of fixed-pattern noise have been
investigated, and techniques have been devised for recognizing and
removing it from the data. The ultimate signal-to-noise ratio achievable
with the spectrograph is essentially limited only by counting
statistics, and values approaching 1000:1 have been obtained. (SECTION:
Astronomical Instrumentation)
Title: Formation of Atomic Emission Lines in the Atmosphere
of Jupiter After the Comet Shoemaker-Levy 9 S Impact
Authors: Carpenter, K. G.; McGrath, M. A.; Yelle, R. V.;
Noll, K. S.; Weaver, H. A.
Publication: American Astronomical Society, DPS Meeting \#27,
\#22.03; Bulletin of the American Astronomical
Society, Vol. 27, p.1118
Publication Date: 06/1995
Origin: ADS
Bibliographic Code: 1995DPS....27.2203C
Abstract
Not Available
Title: An Atlas of Alpha Orionis Obtained with the Goddard
High Resolution Spectrograph on the Hubble Space
Telescope
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.;
Boggess, A.; Carpenter, K. G.; Ebbets, D. C.;
Hutchings, J. B.; Jura, M.; Leckrone, D. S.;
Linsky, J. L.; Maran, S. P.; Savage, B. D.;
Smith, A. M.; Trafton, L. M.; Walter, F. M.;
Weymann, R.; Snow, M.; Randall, C. E.; Ake, T. B.;
Robinson, R. D.; Wahlgren, G.
Publication: Astronomical Journal v.109, p.2706
Publication Date: 06/1995
Origin: AJ; KNUDSEN
AJ/ApJ Keywords: STARS: LATE-TYPE, STARS: INDIVIDUAL: ALPHA ORIONIS
DOI: 10.1086/117484
Bibliographic Code: 1995AJ....109.2706B
Abstract
An atlas of observations of the late-type supergiant a Orionis taken
with the Goddard High Resolution Spectrograph in 1992 September is
presented. We have included identifications of the major features
along with the fully reduced spectrum. The 33 exposures consist of 3
high resolution (R~80,000) and 30 medium resolution (R
~20,000~35,000) observations. The latter provide complete
wavelength coverage from 1980 to 3300 Å.
Title: A numerical study of the coupling coefficients for
pot core transformers
Authors: Howard, T. O.; Carpenter, K. H.
Publication: IEEE Transactions on Magnetics, vol. 31, issue 3,
pp. 2249-2253
Publication Date: 05/1995
Origin: CROSSREF
DOI: 10.1109/20.376237
Bibliographic Code: 1995ITM....31.2249H
Abstract
Not Available
Title: GHRS observations of cool, low-gravity star. 2: Flow
and turbulent velocities in the outer atmosphere of
gamma CRU CIS (M3.4 III)
Authors: Carpenter, Kenneth G.; Robinson, Richard D.;
Judge, Philip G.
Affiliation: AA(NASA/Goddard Space Flight Center, Greenbelt,
Maryland, US), AB(NASA/Goddard Space Flight Center,
Greenbelt, Maryland, US), AC(National Center for
Atmospheric Research, Boulder, Colorado, US)
Publication: Astrophysical Journal, Part 1 (ISSN 0004-637X), vol.
444, no. 1, p. 424-437
Publication Date: 05/1995
Category: Astronomy
Origin: STI
NASA/STI Keywords: ASTRONOMICAL SPECTROSCOPY, COOL STARS, FLOW
VELOCITY, STELLAR ATMOSPHERES, STELLAR SPECTRA,
TURBULENCE, ULTRAVIOLET ASTRONOMY, ABSORPTION
SPECTRA, CHROMOSPHERE, EMISSION SPECTRA, HUBBLE
SPACE TELESCOPE, STELLAR WINDS, ULTRAVIOLET SPECTRA
DOI: 10.1086/175617
Bibliographic Code: 1995ApJ...444..424C
Abstract
The Goddard High Resoulution Spectrograph (GHRS) on the Hubble Space
Telescope (HST) has been used to obtain medium (R = 20,000) and high (R
= 85,000) resoultion UV spectra of chromosphere emission features for
the M3.4 III star gamma Cru. Small Science Aperture (SSA) G270M and
Echelle-B spectra of selected regions in the 2300-2850 A range were
obtained to determine the kinematics of the chromosphere using lines of
C2), Fe2, Co2, Si1/2), Ni2, Mn2, and Mg2. Profiles of C2) (UV 0.01)
lines and fluorescently excited lines of low optical depth indicate
average turbulent velocities (Doppler FWHM) of 30.2 +/- 1.3 and 28.8 +/-
1.3 km/s, respectively. The fluorescent emission lines (mean RV = 21.3
+/- 0.9 km/s) and the wings of the emission components of Fe2 lines
(mean RV = 22.8 +/- 0.4 km/s) are approximately at rest relative to the
radial velocity of the star (21 km/s), while the C2) lines show a modest
inflow (mean RV = 23.1 +/- 0.9 km/s). The more opaque lines of Fe2 and
Mg2 exhibit complex profiles resulting from line formation in an
optically thick, extended expanding atmosphere. The emission wings of
these lines are broadened by multiple scattering, and they are centered
near the photospheric radial velocity. Closer to line center, these
strong lines show a strong blueshifted self-absorption feature (already
seen in IUE data), indicative of formation in an expanding chromosphere,
and a previously unseen dip in the profiles on the red side of line
center. The absorption components, when extracted using simple Gaussian
fits, show strong correlations with the relative optical depths of the
lines. The derived absorption flow velocities converge to the
photospheric velocity as one examines spectra features formed deeper in
the atmosphere. The blueward abosrption velocity increases in magnitude
from about 7 to 14 km/s with increasing line optical depth - the strong
absorptions directly map the acceleration of the outflowing stellar
wind, while the interpretation of the weaker redshifted absorptions is
more ambiguous, indicating either an inflow of material or formation in
an extended, spherically expanding outflow. The Mg2 and Fe2 profiles,
taken together, imply that the wind speed decreases between the
atmospheric layers where the Mg2 and Fe2 self-absorption components are
formed. Interstellar absorptions are seen in the resonance lines of Mg2
(UV 1) and Fe2 (UV1) with zero-volt lower levels, at about -3 km/s,
consistent with models of the interstellar medium in the direction of
gamma Cru. Finally, we have detected the Mg2 'satellite lines' seen in
solar spectra obtained above the limb. In gamma Cru these lines are
probably fluorescently excited by H Ly beta.
Title: Outer layers of a carbon star: The view from the
Hubble Space Telescope
Authors: Johnson, Hollis R.; Ensman, Lisa M.;
Alexander, David R.; Avrett, Eugene H.;
Brown, Alexander; Carpenter, Kenneth G.;
Eriksson, Kjell; Gustafsson, Bengt;
Jorgensen, Uffe G.; Judge, Philip D.;
Linsky, Jeffrey L.; Luttermoser, Donald G.;
Querci, Francois; Querci, Monique;
Robinson, Richard D.; Wing, Robert F.
Affiliation: AA(Indiana Univ., Bloomington, IN, US), AB(Indiana
Univ., Bloomington, IN, US), AC(Wichita State Univ.,
Wichita, KS, US), AD(Wichita State Univ., Wichita,
KS, US), AE(Univ. of Colorado, Boulder, CO, US),
AF(Univ. of Colorado, Boulder, CO, US), AG(Uppsala
Astronomical Observatory, Uppsala, Sweden),
AH(Uppsala Astronomical Observatory, Uppsala,
Sweden), AI(Niels Bohr Institute, Copenhagen,
Denmark), AJ(Niels Bohr Institute, Copenhagen,
Denmark)
Publication: Astrophysical Journal, Part 1 (ISSN 0004-637X), vol.
443, no. 1, p. 281-294
Publication Date: 04/1995
Category: Astronomy
Origin: STI
NASA/STI Keywords: ASYMPTOTIC GIANT BRANCH STARS, CARBON STARS,
CHROMOSPHERE, STELLAR MASS, STELLAR WINDS,
ULTRAVIOLET ASTRONOMY, ULTRAVIOLET SPECTRA, VELOCITY
DISTRIBUTION, FLUORESCENCE, HUBBLE SPACE TELESCOPE,
PHOTOSPHERE, STELLAR ENVELOPES
DOI: 10.1086/175525
Bibliographic Code: 1995ApJ...443..281J
Abstract
To advance our understanding of the relationship between stellar
chromospheres and mass loss, which is a common property of carbon stars
and other asymptotic giant branch stars, we have obtained ultraviolet
spectra of the nearby N-type carbon star UU Aur using the Hubble Space
Telescope (HST). In this paper we describe the HST observations,
identify spectral features in both absorption and emission, and attempt
to infer the velocity field in the chromosphere, upper troposphere, and
circumstellar envelope from spectral line shifts. A mechanism for
producing fluoresced emission to explain a previously unobserved
emission line is proposed. Some related ground-based observations are
also described.
Title: Nutritional science by committee?
Authors: Carpenter, Kenneth J.
Affiliation: Department of Nutritional Sciences, University of
California, Berkeley, California94720, USA
Publication: Nature, Volume 374, Issue 6521, pp. 402 (1995).
Publication Date: 03/1995
Origin: NATURE
Abstract Copyright: (c) 1995: Nature
DOI: 10.1038/374402c0
Bibliographic Code: 1995Natur.374..402C
Abstract
Not Available
Title: MG II H and K profiles in high-liminosity, late-type
stars
Authors: Robinson, R. D.; Carpenter, K. G.
Affiliation: AA(NASA. Goddard Space Flight Center, Greenbelt, MD,
US), AB(NASA. Goddard Space Flight Center,
Greenbelt, MD, US)
Publication: The Astrophysical Journal, Part 1 (ISSN 0004-637X),
vol. 442, no. 1, p. 328-336
Publication Date: 03/1995
Category: Astronomy
Origin: STI
NASA/STI Keywords: ABSORPTANCE, GIANT STARS, K STARS, LINE SPECTRA, M
STARS, MAGNESIUM, STELLAR LUMINOSITY, STELLAR WINDS,
SUPERGIANT STARS, COMPARISON, HUBBLE SPACE
TELESCOPE, IUE, RADIATIVE TRANSFER, SPECTRAL LINE
WIDTH, SPECTRUM ANALYSIS, VELOCITY DISTRIBUTION
DOI: 10.1086/175443
Bibliographic Code: 1995ApJ...442..328R
Abstract
Using high-resolution spectroscopic data taken with the Goddard High
Resolution Spectrographic (GHRS) aboard the Hubble Space Telescope (HST)
and with the International Ultraviolet Explorer (IUE) satellite, we
compare the profiles of the Mg II h and k lines seen in stars with
spectral types ranging from early K through mid-M and luminosities from
giants to supergiants. For all of these stars the lines are broad
emission features with a central absorption. When plotted on a velocity
scale the absorption features of the h and k lines agree very well in
both shape and position, as do the blue wings of the emission component.
The red wings of the emission, however, show a pronounced difference,
with the k line wing consistently shifted to the red of the h line wing.
At present the reason for this discrepancy is unknown, but we suggest
several possibilities, including radiative transfer effects and
high-speed stellar winds.
Title: Fe II Line Profiles as Stellar Wind Diagnostics in M
Giant and Supergiant Stars
Authors: Carpenter, K. G.; Robinson, R. D.
Affiliation: AA(LASP ASA/GSFC), AB(CSCL ASP NASA/GSFC)
Publication: American Astronomical Society, 186th AAS Meeting,
\#22.20; Bulletin of the American Astronomical
Society, Vol. 27, p.844
Publication Date: 03/1995
Origin: AAS
Abstract Copyright: (c) 1995: American Astronomical Society
Bibliographic Code: 1995AAS...186.2220C
Abstract
Detailed study of high resolution, high signal-to-noise chromospheric Fe
II emission line profiles, obtained with the Goddard High Resolution
Spectrograph on the Hubble Space Telescope, provides an opportunity to
probe the flow velocities in the outer atmospheres/winds of cool,
low-gravity stars. We have previously reported seeing the acceleration
of the outflowing wind in such data from several M-giant stars,
including gamma Cru (M3.4 III), mu Gem (M3 IIIab), and alpha Tau (K5
III). Early attempts to do the same with the M-supergiant alpha Ori (M2
Iab) met with limited success, due to the high-opacity of its outer
atmosphere and the significant differences in the character and behavior
of the observed line profiles in the supergiant spectrum. Further
analysis of the GHRS observations of Fe II lines in alpha Ori has now
enabled us to detect the accelerating outflow in it's wind as well. A
detailed comparison of the observed Fe II profiles and the flows
inferred from those profiles, with those for the less-luminous, but
similar Teff M-giant gamma Cru are presented.
Title: Observations of Fe XXI on the RS CVn star HR 1099:
deducing the coronal properties
Authors: Robinson, R. D.; Airapetian, V. S.; Maran, S. P.;
Carpenter, K. G.
Publication: Poster proceedings of IAU Symposium 176, held 9-13
October 1995, Vienna, Austria, Wien: Universitaet,
Institut fuer Astronomie. |c1995, edited by Klaus G.
Strassmeier., p.191
Publication Date: 00/1995
Origin: ADS
Bibliographic Code: 1995IAUS..176P.191R
Abstract
Not Available
Title: Line Identifications in Goddard High Resolution
Spectrograph Observations of Cool, High-Luminosity
Stars
Authors: Carpenter, K. G.; Robinson, R. D.
Publication: Workshop on Laboratory and astronomical high
resolution spectra. Astronomical Society of the
Pacific Conference Series; Proceedings of ASP
Conference no. 81 held in Brussels; Belgium 29
August - 2 September 1994 in honour of the 150th
birthday of Charles Vievez (1844-1890) the pioneer
of astronomical spectroscopy in Belgium; San
Francisco: Astronomical Society of the Pacific
(ASP); |c1995; edited by A.J. Sauval, R. Blomme, and
N. Grevesse, p.559
Publication Date: 00/1995
Origin: ADS
Bibliographic Code: 1995ASPC...81..559C
Abstract
Not Available
Title: The effects of transverse vibration on the
performance of an axial groove wick heat pipe
Authors: Carpenter, Kenneth A.
Affiliation: AA(B, OH.)
Publication: M.S. Thesis Air Force Inst. of Tech.,
Wright-Patterson AFB, OH. School of Engineering.
Publication Date: 12/1994
Category: Fluid Mechanics and Heat Transfer
Origin: STI
NASA/STI Keywords: AXIAL FLOW, GROOVES, HEAT PIPES, SINE WAVES,
TRANSVERSE OSCILLATION, VIBRATION EFFECTS, WICKS,
WORKING FLUIDS, DEGRADATION, DETERIORATION,
PERFORMANCE TESTS, STATIC TESTS, VIBRATION
Bibliographic Code: 1994aifo.reptT....C
Abstract
An experimental investigation was performed to determine the effects of
transverse vibrations on the performance of an ammonia/aluminum axial
groove wick heat pipe. Theoretical calculations predicted a performance
degradation due to the working fluid being shaken out of the upper
capillary grooves. A benchtop shaker was used to apply transverse,
sinusoidal vibrations of 30, 35, and 40 Hertz, corresponding to peak
acceleration amplitudes of 1.84g, 2.50g, and 3.27g, respectively.
Maximum heat throughput, Q(sub max), of the vibrating heat pipe was
measured. A comparison of these values and static Q(sub max) values
indicated a degradation in heat pipe performance. A mean performance
deterioration of 27.6 Watts was measured for the 1.84g case, an average
degradation of 12.9 percent from static heat pipe performance. At 2.50g
peak acceleration the degradation rose to 37.3 watts, an average
decrease of 14.8 percent from static performance. An average
deterioration in performance of 28.1 percent was recorded for the 3.27g
case. This amounted to a mean performance degradation of 69.3 watts. The
results of this investigation revealed that transverse, sinusoidal
vibrations have a detrimental impact on the performance of an
ammonia/axial groove wick heat pipe. Further, the performance
degradation increases with increasing vibrational peak acceleration
amplitude.
Title: GHRS Spectra of alpha Tau
Authors: Carpenter, K.; Robinson, R.; Judge, P.
Affiliation: AA(LASP/NASA-GSFC), AB(CSC@LASP/NASA-GSFC),
AC(HAO/NCAR)
Publication: American Astronomical Society, 185th AAS Meeting,
\#45.09; Bulletin of the American Astronomical
Society, Vol. 26, p.1380
Publication Date: 12/1994
Origin: AAS
Abstract Copyright: (c) 1994: American Astronomical Society
Bibliographic Code: 1994AAS...185.4509C
Abstract
Goddard High Resolution Spectrograph (GHRS) observations of the K5 giant
alpha Tau were obtained on 8 April 1994. Spectra of approximately 40
Angstroms-wide regions centered near 1300, 1550, 1660, 1995, 2340, 2760,
and 2800 Angstroms were obtained through the Small Science Aperture
(SSA) with medium resolution (R=20,000) gratings. These data provide
high-precision profiles of a variety of lines formed in the stellar
chromosphere and transition region, including O I, Fe II, C I, C II], Si
II], Mg II, and C IV. Self-reversed emission from O I, Fe II, and Mg II
provide information on the wind flow velocities, with all three ions
showing both red and blue-shifted absorption components, as seen
previously in the Fe II emission from the later-type giants gamma Cru
and mu Gem. The first evidence for hot plasma in the outer atmosphere of
alpha Tau is seen in the G160M spectrum centered near 1550 Angstroms@.
This spectrum shows very broad, but distinct features due to the C IV
(UV 1) doublet, as well as a myriad of much narrower emissions formed at
cooler temperatures, such as (fluorescent) Fe II and perhaps Ni II and C
I. C I (UV 2) is seen in emission and a comparison of its flux with that
in C I (UV 32) will allow an estimation of the C I chromospheric column
density. Multiple observations of the C II] (UV 0.01) intercombination
multiplet were obtained to search for evidence of shocks and/or
propagating waves. Results of that search will be presented. Finally,
very high-resolution (R=85,000) echelle spectra were obtained of the Mg
II resonance doublet near 2800 Angstroms@. These emission features show
strong interstellar, stellar, and circumstellar absorption components
at, above, and below the stellar rest velocity.
Title: Coronal Heating Mechanisms: A Search for Microflare
Activity on YZ CMi
Authors: Robinson, R. D.; Carpenter, K. G.; Percival, J. W.
Affiliation: AA(CSC), AB(LASP/GSFC/NASA), AC(Univ of Wisconsin)
Publication: American Astronomical Society, 185th AAS Meeting,
\#45.06; Bulletin of the American Astronomical
Society, Vol. 26, p.1380
Publication Date: 12/1994
Origin: AAS
Abstract Copyright: (c) 1994: American Astronomical Society
Bibliographic Code: 1994AAS...185.4506R
Abstract
We report on time series photometric observations of the dM4.5e flare
star YZ CMi taken in 1993 Nov with the High Speed Photometer aboard the
Hubble Space Telescope. The data consist of five 30 minute time
sequences, with a sampling rate of 0.01s, which were taken through the
F240W filter (centered at 240nm with a 800 Angstroms width). This setup
was selected since the flare energy is expected to be large and the
stellar background is small at these wavelengths. The observations show
a stellar background of 120 counts s(-1) on which are superimposed well
defined flare events ranging in integrated energy from 10(28) to 10(30)
ergs, as well as longer term variations with an amplitude of up to 50%
of the continuum intensity and time scales ranging from several minutes
to hours. These results are compared with data from the dM8e flare star
CN Leo, obtained earlier with the same experimental setup. CN Leo has a
quiescent X-ray flux which is 1/30 that of YZ CMi, but had a higher
occurrence rate of microflares. On the other hand, the stellar UV
background, which must be chromospheric in origin, is less than 1/25th
that seen on YZ CMi. This suggests a link between chromospheric and
coronal heating.
Title: GHRS and IUE Observations of the Symbiotic Binary CI
Cygni
Authors: Jalakas, M.; Stencel, R. E.; Carpenter, K. G.;
Robinson, R. D.
Affiliation: AA(U.Denver Obs.), AB(LASP, NASA-Goddard), AC(CSC)
Publication: American Astronomical Society, 185th AAS Meeting,
\#21.11; Bulletin of the American Astronomical
Society, Vol. 26, p.1345
Publication Date: 12/1994
Origin: AAS
Abstract Copyright: (c) 1994: American Astronomical Society
Bibliographic Code: 1994AAS...185.2111J
Abstract
The interacting symbiotic binary star, CI Cygni, is a system which
consists of a hot star orbiting a red giant. Matter from the larger star
is being transfered to the smaller one. Both IUE and more recently, the
Goddard High Resolution Spectrograph on HST have detected variable
ultraviolet emission lines produced by this transfer. Phase-dependent
changes to the doppler velocity of the matter allow us to map the
direction of the flow. Using the HST snd IUE spectrometers, we
re-examined two different types of lines (resonance and
intercombination) which had been reported to show velocity differences.
We will present an analysis of these data showing the relative locations
of high and low density features in the matter transfer in this system.
The lead authors are pleased to acknowledge partial support for this
effort through NASA grant NAG5-2368 to the University of Denver.
Title: The Goddard High Resolution Spectrograph:
Instrument, goals, and science results
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.;
Boggess, A.; Carpenter, K. G.; Ebbets, D. C.;
Hutchings, J. B.; Jura, M.; Leckrone, D. S.;
Linsky, J. L.; Maran, S. P.; Savage, B. D.;
Smith, A. M.; Trafton, L. M.; Walter, F. M.;
Weymann, R. J.; Ake, T. B.; Bruhweiler, F.;
Cardelli, J. A.; Lindler, D. J.; Malumuth, E.;
Randall, C. E.; Robinson, R.; Shore, S. N.;
Wahlgren, G.
Affiliation: AA(University of Colorado, Boulder, CO, US),
AB(University of Colorado, Boulder, CO, US),
AC(University of California, San Diego, La Jolla,
CA, US), AD(University of California, San Diego, La
Jolla, CA, US), AE(NASA. Goddard Space Flight
Center, Greenbelt, MD, US), AF(NASA. Goddard Space
Flight Center, Greenbelt, MD, US), AG(Dominion
Astrophysical Observatory, Victoria, BC, US),
AH(Dominion Astrophysical Observatory, Victoria, BC,
US), AI(NASA. Goddard Space Flight Center,
Greenbelt, MD, US), AJ(NASA. Goddard Space Flight
Center, Greenbelt, MD, US)
Publication: Astronomical Society of the Pacific, Publications
(ISSN 0004-6280), vol. 106, no. 702, p. 890-908
Publication Date: 08/1994
Category: Spacecraft Instrumentation
Origin: STI
NASA/STI Keywords: ASTRONOMICAL SPECTROSCOPY, HIGH RESOLUTION,
INTERSTELLAR MATTER, SPECTRAL RESOLUTION, STELLAR
ATMOSPHERES, STELLAR EVOLUTION, ABUNDANCE, CHEMICAL
EVOLUTION, HUBBLE SPACE TELESCOPE, MASS TRANSFER,
SEYFERT GALAXIES, ULTRAVIOLET SPECTRA
DOI: 10.1086/133457
Bibliographic Code: 1994PASP..106..890B
Abstract
The Goddard High Resolution Spectrograph (GHRS), currently in Earth
orbit on the Hubble Space Telescope (HST), operates in the wavelength
range 1150-3200 A with spectral resolutions (lambda/delta lambda) of
approximately 2 x 103, 2 x 104, and 1 x
103. The instrument and its development from inception, its
current status, the approach to operations, representative results in
the major areas of the scientific goals, and prospects for the future
are described.
Title: Reptilian Offspring. (Book Reviews: Dinosaur Eggs
and Babies.)
Book Authors: Carpenter, Kenneth; Horner, John R.
Review Author: Padian, Kevin
Publication: Science, Volume 265, Issue 5171, pp. 550-551
Publication Date: 07/1994
Origin: JSTOR
Bibliographic Code: 1994Sci...265..550C
Abstract
Not Available
Title: Spectra and Chromospheres of Carbon and M Stars -
CYCLE4 Medium
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#5359
Publication Date: 07/1994
Origin: HST
Keywords: HST Proposal ID \#5359 COOL STARS STELLAR ATMOSPHERES
Bibliographic Code: 1994hst..prop.5359C
Abstract
We propose to use the Faint Object Spectrograph (FOS) and the Goddard
High-Resolution Spectrograph (GHRS) on the HST to obtain ultraviolet
spectra of visually bright N-type carbon stars and late M-giant stars.
These spectra, obtainable only with HST, will be used with theoretical
models to infer the temperature and density structure and the velocity
fields of the outer atmosphere in these evolutionarily advanced,
non-mira giants. In anticipation of this effort, we have already pushed
IUE to its limit to obtain both low-resolution, and, where possible,
high-resolution spectra of several M, S, and C stars, and these have
been analyzed and published. Based upon the observed line profiles and
continua, we will construct semi-empirical non-LTE models in both
plane-parallel geometry and spherical geometry, including velocity
fields, by attaching a chromosphere to theoretical photospheric models.
Two-component models will be studied. Using these and ab-initio
hydrodynamic models, we will examine the mechanisms responsible for
chromospheric heating and mass loss. A full range of supporting
ground-based observations will be undertaken to permit us to connect
models of the photospheres, chromospheres, and circumstellar shells.
Title: The Chromosphere of Alpha Tau - Cycle 4 Medium
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#5358
Publication Date: 07/1994
Origin: HST
Keywords: HST Proposal ID \#5358 COOL STARS STELLAR ATMOSPHERES
Bibliographic Code: 1994hst..prop.5358C
Abstract
We propose observations of the K5 III star Alpha Tau using the Goddard
High-Resolution Spectrograph (GHRS), to follow-up on the exciting
initial SAO observations of this star and the SV observations of the K5
III hybrid star Gamma Dra. These data will also allow a detailed
comparison of its spectrum and the thermodynamic properties of its outer
atmosphere with those of the cooler M giant and supergiant stars Gamma
Cru and Alpha Ori, observed during previous cycles. We shall check for
variations in the C II downflow discovered in the SAO observations and
search for evidence of systematic flows in other emission lines. We
shall make detailed comparisons of the chromospheric emission lines and
wind signatures in the UV spectra of two stars of the same spectral
class, where one is a hybrid and one is not. We shall search for
evidence of shocks and/or propagating waves in the line variations
predicted by our recent calculations. We will also determine the
variation of wind velocity with height using semi-empirical non-LTE
models assuming spherical symmetry, search for evidence of circumstellar
and interstellar absorptions on resonance lines of O I, Fe II, and Mg
II, and compare the short-wavelength continuum measured in this star
with that detected in observations of Gamma Dra, Gamma Cru and Alpha
Ori.
Title: GHRS observations of cool, low-gravity stars. 1: The
far-ultraviolet spectrum of alpha Orionis (M2 Iab)
Authors: Carpenter, Kenneth G.; Robinson, Richard D.;
Wahlgren, Glenn M.; Linsky, Jeffrey L.;
Brown, Alexander
Affiliation: AA(NASA. Goddard Space Flight Center, Greenbelt, MD,
US), AB(NASA. Goddard Space Flight Center,
Greenbelt, MD, US), AC(NASA. Goddard Space Flight
Center, Greenbelt, MD, US), AD(NASA. Goddard Space
Flight Center, Greenbelt, MD, US), AE(University of
Colorado, Boulder, CO, US)
Publication: Astrophysical Journal, Part 1 (ISSN 0004-637X), vol.
428, no. 1, p. 329-344
Publication Date: 06/1994
Category: Astrophysics
Origin: STI
NASA/STI Keywords: ABSORPTION SPECTRA, CHROMOSPHERE, LINE SPECTRA,
STELLAR ENVELOPES, SUPERGIANT STARS, ULTRAVIOLET
SPECTRA, HIGH RESOLUTION, HUBBLE SPACE TELESCOPE,
IUE, SPECTROGRAPHS, STELLAR MODELS
DOI: 10.1086/174244
Bibliographic Code: 1994ApJ...428..329C
Abstract
We present far-UV (1200-1930 A) observations of the prototypical red
supergiant star alpha Ori, obtained with the Goddard High Resolution
Spectrograph (GHRS) on the Hubble Space Telescope (HST). The
observations, obtained in both low- (G140L) and medium- (G160/200M)
resolution modes, unambiguously confirm that the UV 'continuum'
tentatively seen with (IUE) is in fact a true continuum and is not due
to a blend of numerous faint emission features or scattering inside the
IUE spectrograph. This continuum appears to originate in the
chromospheric of the star at temperatures ranging from 3000-5000 K, and
we argue that it is not related to previously reported putative
companions or to bright spots on the stellar disk. Its stellar origin is
further confirmed by overlying atomic and molecular absorptions from the
chromosphere and circumstellar shell. The dominant structure in this
spectral region is due to nine strong, broad absorption bands of the
fourth-positive A-X system of CO, superposed on this continuum in the
1300-1600 A region. Modeling of this CO absorption indicates that it
originates in the circumstellar shell in material characterized by T =
500 K, N(CO) = 1.0 x 1018 per sq cm, and Vturb =
5.0 km per sec. The numerous chromospheric emission features are
attributed mostly to fluorescent lines of Fe II and Cr II (both pumped
by Lyman Alpha) and S I lines, plus a few lines of O I, C I, and Si II.
The O I and C I UV 2 multiplets are very deficient in flux, compared to
both the flux observed in lines originating from common upper levels but
with markedly weaker intrinsic strength (i.e., O I UV 146 and C I UV 32)
and to the UV 2 line fluxes seen in other cool, less luminous stars.
This deficiency appears to be caused by strong self-absorption of these
resonance lines in the circumstellar shell and/or upper chromosphere of
alpha Ori. Atomic absorption features, primarily due to C I and Fe II
are clearly seen in the G160M spectrum centered near 1655 A. These Fe II
features are formed at temperatures that can occur only in the
chromosphere of the star and are clearly not photospheric or
circumstellar in origin.
Title: Examining the corona of HR 1099 with the Hubble
Space Telescope.
Authors: Robinson, R. D.; Maran, S. P.; Carpenter, K. G.;
Brandt, J. C.; Linsky, J. L.
Publication: Bull. Am. Astron. Soc., Vol. 26, No. 2, p. 865
Publication Date: 05/1994
Origin: ARI
ARI Keywords: Hubble Space Telescope, RS CVn Stars: UV Spectra,
Stellar Coronae: UV Spectra, Stellar Coronae: RS CVn
Stars
Bibliographic Code: 1994BAAS...26..865R
Abstract
Not Available
Title: Examining the Corona of HR 1099 with the Hubble
Space Telescope
Authors: Robinson, R. D.; Maran, S. P.; Carpenter, K. G.;
Brandt, J. C.; Linsky, J. L.
Affiliation: AA(CSC), AB(LASP@NASA-GSFC), AC(LASP@NASA-GSFC),
AD(U. Colorado, LASP), AE(JILA)
Publication: American Astronomical Society, 184th AAS Meeting,
\#05.15; Bulletin of the American Astronomical
Society, Vol. 26, p.865
Publication Date: 05/1994
Origin: AAS
Abstract Copyright: (c) 1994: American Astronomical Society
Bibliographic Code: 1994AAS...184.0515R
Abstract
A pilot program for the study of stellar coronae through ultraviolet
diagnostic lines is in progress with the Goddard High Resolution
Spectrograph on the Hubble Space Telescope. An initial result of this
program was the detection of the coronal emission line of Fe XXI at 1354
Angstroms in the quiescent spectrum of the dMe star AU Mic (ApJ 421,
800, 1994). The line appeared to be symmetrical, had no measurable
radial velocity with respect to the stellar rest frame, and had a width
which was consistent with a thermal gas of temperature 10(7) K,
suggesting very small turbulence within the formation region. In March
1994, we observed the RS CVn binary HR 1099 = HD 22468 (K1 IV + G5 IV )
using instrumental settings identical to those employed with AU Mic, but
with the added benefit of the recently-installed HST corrective optics
(COSTAR). Each exposure was bracketed by observations of an on-board
wavelength calibration lamp. The results of the series of eight
27-minute integrations, obtained at one-orbit intervals, will be
presented and compared with the AU Mic spectrum.
Title: HST Observations of the Chromosphere of a Carbon
Star
Authors: Ensman, L. M.; Johnson, H. R.; Carpenter, K. G.;
Robinson, R. D.; Luttermoser, D.
Affiliation: AA(Indiana Univ.), AB(Indiana Univ.), AC(LASP at
NASA/GSFC), AD(CSCN at NASA/GSFC), AE(CSCN at
NASA/GSFC), AF(CSCN at NASA/GSFC)
Publication: American Astronomical Society, 184th AAS Meeting,
\#05.06; Bulletin of the American Astronomical
Society, Vol. 26, p.863
Publication Date: 05/1994
Origin: AAS
Abstract Copyright: (c) 1994: American Astronomical Society
Bibliographic Code: 1994AAS...184.0506E
Abstract
Ultraviolet spectra from the first Hubble Space Telescope observations
of a carbon star are presented, as well as line identifications and an
initial analysis of the velocity structure of the emitting region. Two
spectra of UU Aur (HD 46687, type N3; C5,3) have been obtained. In the
lower-resolution FOS spectrum (2310 -- 3275 Angstroms), UV emission
lines of Mg I, Mg II, and Fe II, fluoresced lines of Fe I and II,
semi-forbidden emission from C II, Si II, and Al II, absorption lines of
Fe I and Ti II, and absorption by CH and CaCl have been identified. In
the high resolution GHRS spectrum, which covers a 50 Angstroms region
around the Mg II h and k emission lines, overlying Mg II and Mn I
absorption and two fluoresced Fe I lines have been resolved. The Mg II,
and perhaps the Ti II, absorption appears to be interstellar. UV
emission lines of predominantly singly ionized metals indicate the
existence of a chromosphere at ~ 5000 K. In UU Aur, the Mg II emission
clearly arises in material which is flowing away from the star at 35--60
km/s. Shifts of the Fe II emission lines support the conclusion that the
chromosphere is expanding at highly supersonic velocities. However,
overlying Mn I absorption must be due to stationary material further
out. The forbidden and fluoresced lines also come from a region(s) with
negligible velocity. These data imply that shocks may form in the
atmospheres of carbon stars and thus be a mechanism for chromospheric
heating and mass loss. In fact, previous semi-empirical chromospheric
models of the carbon star TX Psc (Luttermoser, Johnson, Avrett, and
Loeser 1989) indicate a similar shock-like velocity field. Luttermoser,
D., Johnson, H. R., Avrett, G., and Loeser, R. 1989, ApJ 345, 543.
Title: GHRS Observations of the M-Giant MU GEM
Authors: Carpenter, K. G.; Robinson, R. D.; Johnson, H. R.;
Ensman, L. M.
Affiliation: AA(LASP@NASA-GSFC), AB(CSC@NASA-GSFC), AC(Indiana
U.), AD(Indiana U.)
Publication: American Astronomical Society, 184th AAS Meeting,
\#05.05; Bulletin of the American Astronomical
Society, Vol. 26, p.863
Publication Date: 05/1994
Origin: AAS
Abstract Copyright: (c) 1994: American Astronomical Society
Bibliographic Code: 1994AAS...184.0505C
Abstract
The ultraviolet spectrum of the M-giant mu Gem (M3 IIIab) is sampled at
selected important wavelengths with the Goddard High Resolution
Spectrograph (GHRS) on the Hubble Space Telescope (HST). The wavelength
regions are chosen to include lines sensitive to turbulence and flow
velocities in the stellar chromosphere and wind acceleration region, as
well as some fiducial photospheric absorption features. The dynamics of
the outer atmosphere of mu Gem are examined using the observed profiles
and positions of chromospheric emission lines of C II, Fe II, Mg II, Fe
I, referenced to photospheric absorption lines of Fe I. The content of
the spectra and the inferred flow and turbulent velocities are compared
to those found for the other cool, low-gravity stars observed with GHRS,
including alpha Ori (M2 Iab) and gamma Cru (M3.4 III).
Title: Ultraviolet and Radio Observations of the Young
Rapidly Rotating k0 Dwarf Star HD197890
Authors: Robinson, R. D.; Carpenter, K. G.; Slee, O. B.;
Nelson, G. J.; Stewart, R. T.
Publication: R.A.S. MONTHLY NOTICES V.267, NO. 4/APR15, P. 918,
1994
Publication Date: 04/1994
Origin: KNUDSEN; MNRAS
MNRAS Keywords: stars: activity - stars: individual: HD 197890 -
stars: late-type - stars: rotation - radio
continuum: stars - ultraviolet: stars
Bibliographic Code: 1994MNRAS.267..918R
Abstract
We present the results of UV observations taken with the International
Ultraviolet Explorer (IUE) satellite and microwave observations obtained
with the Australia Telescope during an observing campaign of the rapidly
rotating K0 dwarf star III) 197890, nicknamed `Speedy Mic'. This star
was recently recognized as a powerful, transient EUV source by the ROSAT
WFC, and subsequent investigation showed it to be a ZAMS or possibly a
PMS dwarf which may be a member of the Local Association. Our
observations show it to have strong, variable UV emission lines near the
`saturation' levels. The radio observations show a level of `quiescent'
emission consistent with other rapidly rotating stars, but there is no
evidence for the large flux variations that normally characterize the
time history of such objects.
Title: Observing stellar coronae with the Goddard High
Resolution Spectrograph. 1: The dMe star AU
microscopoii
Authors: Maran, S. P.; Robinson, R. D.; Shore, S. N.;
Brosius, J. W.; Carpenter, K. G.; Woodgate, B. E.;
Linsky, J. L.; Brown, A.; Byrne, P. B.; Kundu, M. R.;
White, S.; Brandt, J. C.; Shine, R. A.;
Walter, F. M.
Affiliation: AA(NASA. Goddard Space Flight Center, Greenbelt, MD,
US), AB(NASA. Goddard Space Flight Center,
Greenbelt, MD, US), AC(NASA. Goddard Space Flight
Center, Greenbelt, MD, US), AD(NASA. Goddard Space
Flight Center, Greenbelt, MD, US), AE(NASA. Goddard
Space Flight Center, Greenbelt, MD, US), AF(NASA.
Goddard Space Flight Center, Greenbelt, MD, US),
AG(Univ. of Colorado, Boulder, CO, US), AH(Univ. of
Colorado, Boulder, CO, US), AI(Armagh Observatory,
Northern Ireland, UK), AJ(Armagh Observatory,
Northern Ireland, UK)
Publication: Astrophysical Journal, Part 1 (ISSN 0004-637X), vol.
421, no. 2, p. 800-808
Publication Date: 02/1994
Category: Astronomy
Origin: STI
NASA/STI Keywords: LATE STARS, SPACEBORNE ASTRONOMY, STELLAR CORONAS,
STELLAR SPECTRA, ULTRAVIOLET ASTRONOMY, ULTRAVIOLET
SPECTRA, ATOMIC SPECTRA, EMISSION SPECTRA, HUBBLE
SPACE TELESCOPE, LINE SPECTRA, SPECTROGRAPHS,
STELLAR MODELS
DOI: 10.1086/173692
Bibliographic Code: 1994ApJ...421..800M
Abstract
We report on an observation of AU Mic taken with the Goddard High
Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope. The
data consist of a rapid sequence of spectra covering the wavelength
range 1345-1375 A with a spectral resolution of 10,000. The observations
were originally intended to search for spectral variations during
flares. No flares were detected during the 3.5 hr of monitoring. A
method of reducing the noise while combining the individual spectra in
the time series is described which resulted in the elimination of half
of the noise while rejecting only a small fraction of the stellar
signal. The resultant spectrum was of sufficient quality to allow the
detection of emission lines with an integrated flux of 10-15
ergs/sq cm(sec) or greater. Lines of C I, O I, O V, Cl I, and Fe XXI
were detected. This is the first indisputable detection of the 1354 A Fe
XXI line, formed at T approximately = 107 K, on a star other
than the Sun. The line was well resolved and displayed no significant
bulk motions or profile asymmetry. From the upper limit on the observed
line width, we derive an upper limit of 38 km/s for the turbulent
velocity in the 107 K plasma. An upper limit is derived for
the flux of the 1349 A Fe XII line, formed at T approximately = 1.3 x
106 K. These data are combined with contemporaneous GHRS and
International Ultraviolet Explorer (IUE) data to derive the volume
emission measure distribution of AU Mic over the temperature range
104-107 K. Models of coronal loops in hydrostatic
equilibrium are consistent with the observed volume emission measures of
the coronal lines. The fraction of the stellar surface covered by the
footprints of the loops depends upon the loop length and is less than
14% for lengths smaller than the stellar radius. From the upper limit to
the estimated width of the Fe XXI line profile we find that the we
cannot rule out Alfven wave dissipation as a possible contributor to the
required quiescent loop heating rate.
Title: Search for CO absorption bands in IUE
far-ultraviolet spectra of cool stars
Authors: Gessner, S. E.; Carpenter, K. G.; Robinson, R. D.
Affiliation: AA(NASA. Goddard Space Flight Center, Greenbelt, MD,
US), AB(NASA. Goddard Space Flight Center,
Greenbelt, MD, US), AC(NASA. Goddard Space Flight
Center, Greenbelt, MD, US)
Publication: Astronomical Journal (ISSN 0004-6256), vol. 107, no.
2, p. 747-750
Publication Date: 02/1994
Category: Astrophysics
Origin: STI
NASA/STI Keywords: ABSORPTION SPECTRA, CARBON MONOXIDE, CHROMOSPHERE,
COOL STARS, FAR ULTRAVIOLET RADIATION, SPACEBORNE
ASTRONOMY, STELLAR ENVELOPES, STELLAR SPECTRA,
SUPERGIANT STARS, ULTRAVIOLET ASTRONOMY, ULTRAVIOLET
SPECTRA, CONTINUUMS, HUBBLE SPACE TELESCOPE, IUE,
STELLAR GRAVITATION
DOI: 10.1086/116894
Bibliographic Code: 1994AJ....107..747G
Abstract
Observations of the red supergiant (M2 Iab) alpha Ori with the Goddard
High Resolution Spectrograph (GHRS) on board the Hubble Space Telescope
(HST) have provided an unambiguous detection of a far-ultraviolet
(far-UV) chromospheric continuum on which are superposed strong
molecular absorption bands. The absorption bands have been identified by
Carpenter et al. (1994) with the fourth-positive A-X system of CO and
are likely formed in the circumstellar shell. Comparison of these GHRS
data with archival International Ultraviolet Explorer (IUE) spectra of
alpha Ori indicates that both the continuum and the CO absorption
features can be seen with IUE, especially if multiple IUE spectra,
reduced with the post-1981 IUESIPS extraction procedure (i.e., with an
oversampling slit), are carefully coadded to increase the signal to
noise over that obtainable with a single spectrum. We therefore
initiated a program, utilizing both new and archival IUE Short
Wavelength Prime (SWP) spectra, to survey 15 cool, low-gravity stars,
including alpha Ori, for the presence of these two new chromospheric and
circumstellar shell diagnostics. We establish positive detections of
far-UV stellar continua, well above estimated IUE in-order scattered
light levels, in spectra of all of the program stars. However,
well-defined CO absorption features are seen only in the alpha Ori
spectra, even though spectra of most of the program stars have
sufficient signal to noise to allow the dectection of features of
comparable magnitude to the absorptions seen in alpha Ori. Clearly if CO
is present in the circumstellar environments of any of these stars, it
is at much lower column densities.
Title: Coordinated Space and Ground-Based Observations of
the Flare Star YZ CMi
Authors: Carpenter, Kenneth G.
Publication: IUE Proposal ID \#YZRKC
Publication Date: 00/1994
Origin: IUE
Bibliographic Code: 1994iue..prop.4768C
Abstract
We propose IUE ultraviolet observations of the flare star YZ CMi to
complement high time resolution data to be acquired with the Goddard
High Resolution Spectrograph on Hubble Space Telescope and other ground
and space-based observatories including the AAT, ROSAT, and EUVE. The
HST observations are designed to search for the signature of downflowing
proton beams during flare events and to estimate their importance in
providing the energy that powers the flare. These IUE observations,
which include the full range of transition region and chromospheric
lines, are critical to determining the energy balance and atmospheric
structure of any flare observed. The extended dataset, including
non-flare spectra, will allow us to characterize the overall activity
level of the star at the time of the observations, and thus place the
events in the proper context.
Title: A Search For Microflaring Activity on dMe Flare
Stars
Authors: Robinson, R. D.; Carpenter, K. G.; Percival, J. W.
Publication: Cool Stars; Stellar Systems; and the Sun; Eighth
Cambridge Workshop. Astronomical Society of the
Pacific Conference Series, Vol. 64; Proceedings of
the 8th Cambridge Workshop; held in Athens, Georgia;
October 11-14; 1993; San Francisco: Astronomical
Society of the Pacific (ASP); |c1994; edited by
Jean-Pierre Caillault, p.456
Publication Date: 00/1994
Origin: ADS
Bibliographic Code: 1994ASPC...64..456R
Abstract
Not Available
Title: Modeling the Ultraviolet Photospheric Spectrum of
Cool Stars: alpha ORI (M2 Iab)
Authors: Wahlgren, Glenn M.; Carpenter, Kenneth C.
Publication: Cool Stars; Stellar Systems; and the Sun; Eighth
Cambridge Workshop. Astronomical Society of the
Pacific Conference Series, Vol. 64; Proceedings of
the 8th Cambridge Workshop; held in Athens, Georgia;
October 11-14; 1993; San Francisco: Astronomical
Society of the Pacific (ASP); |c1994; edited by
Jean-Pierre Caillault, p.65
Publication Date: 00/1994
Origin: ADS
Bibliographic Code: 1994ASPC...64...65W
Abstract
Not Available
Title: GHRS Observations and Analysis of the 0 I and C I
Resonance Lines in the UV Spectrum of alpha ORI (M2
Iab)
Authors: Carpenter, Kenneth G.; Robinson, Richard D.;
Judge, Philip G.; Ebbets, Dennis C.; Brandt, John C.
Publication: Cool Stars; Stellar Systems; and the Sun; Eighth
Cambridge Workshop. Astronomical Society of the
Pacific Conference Series, Vol. 64; Proceedings of
the 8th Cambridge Workshop; held in Athens, Georgia;
October 11-14; 1993; San Francisco: Astronomical
Society of the Pacific (ASP); |c1994; edited by
Jean-Pierre Caillault, p.56
Publication Date: 00/1994
Origin: ADS
Bibliographic Code: 1994ASPC...64...56C
Abstract
Not Available
Title: On the Weakness of C I and O I Resonance Line
Emission from the Chromosphere of alpha Ori.
Authors: Carpenter, K.; Robinson, R.; Judge, P.; Ebbets, D.;
Brandt, J.
Affiliation: AA(LASP-NASA/GSFC), AB(CSC), AC(HAO/NCAR), AD(BASG),
AE(UCO)
Publication: American Astronomical Society, 183rd AAS Meeting,
\#15.04; Bulletin of the American Astronomical
Society, Vol. 25, p.1313
Publication Date: 12/1993
Origin: AAS
Abstract Copyright: (c) 1993: American Astronomical Society
Bibliographic Code: 1993BAAS...25Q1313C
Abstract
The resonance lines from multiplets UV 2 of both O I and C I are
typically quite strong in emission in the far-UV spectrum of cool stars.
However, in the prototypical M-supergiant alpha Ori, these lines are
remarkably weak, although other transitions from the same upper energy
levels, O I (UV 146) and C I (UV 32), are observed in strong emission
despite their much weaker intrinsic strengths. Due to the presence of
many lines from other species in the regions around the UV 2 multiplets
of O I and C I near 1302 Angstroms and 1655 Angstroms, the lines of
interest suffer severe blending and progress in understanding this flux
deficiency is difficult based on low resolution IUE and GHRS data. We
have therefore obtained medium resolution (R=10,000) GHRS spectra of
alpha Ori of these complex spectral regions, as well as the regions
around the O I (UV 146) and C I (UV 32) lines near 1640 Angstroms and
1993 Angstroms, respectively, to resolve the various contributors and
allow detailed study of this phenomenon. In this paper, we present the
spectra and discuss the formation of the O I, C I, Fe II, and S I lines
which they clearly resolve. Semi-empirical modeling of the outer
atmosphere of alpha Ori and detailed radiative transfer calculations are
used to study the creation and destruction of O I and C I photons.
Title: A search for proton beams during flares on AU
Microscopii
Authors: Robinson, R. D.; Carpenter, K. G.; Woodgate, B. E.;
Maran, S. P.
Affiliation: AA(Computer Sciences Corp.; NASA, Goddard Space
Flight Center, Greenbelt, MD), AB(NASA, Goddard
Space Flight Center, Greenbelt, MD), AC(NASA,
Goddard Space Flight Center, Greenbelt, MD),
AD(NASA, Goddard Space Flight Center, Greenbelt, MD)
Publication: Astrophysical Journal, Part 1 (ISSN 0004-637X), vol.
414, no. 2, p. 872-876.
Publication Date: 09/1993
Category: Astrophysics
Origin: STI
NASA/STI Keywords: DWARF STARS, PROTON BEAMS, STELLAR ACTIVITY, STELLAR
FLARES, STELLAR MODELS, ENERGY BUDGETS, LYMAN ALPHA
RADIATION, SPACEBORNE ASTRONOMY, STELLAR MAGNETIC
FIELDS, ULTRAVIOLET RADIATION
DOI: 10.1086/173129
Bibliographic Code: 1993ApJ...414..872R
Abstract
We report the results of a coordinated observing campaign on the active
M dwarf star AU Mic. The purpose of the campaign was to search for
evidence of proton beams during the impulsive phase of stellar flares
and to determine whether the energy contained in these beams represented
a significant fraction of the energy budget of the flare. During a total
of 3.5 hr of monitoring a small flare was observed simultaneously by the
HST, IUE, and the AAT. This event, which had a total optical + UV
emission of 1.3 x 10 exp 32 ergs, occurred during the decay phase of a
much larger event and showed no evidence for a proton beam with an
energy greater than a few times 10 exp 29 ergs/s. This is comparable to
the maximum energy flux released by the flare, though this energy
release rate must occur over a time interval much shorter than that of
the impulsive phase itself. We conclude that the proton beams may be
capable of transporting some energy during the impulsive phase of a
flare, but that they are unlikely to be the major contributor, at least
for this particular event.
Title: The Chromosphere of Alpha Tau - CYC3
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#4490
Publication Date: 07/1993
Origin: HST
Keywords: HST Proposal ID \#4490
Bibliographic Code: 1993hst..prop.4490C
Abstract
We propose observations of the K5 III star Alpha Tau using the Goddard
High-Resolution Spectrograph (GHRS), to follow-up on the exciting
initial SAO observations of this star and the SV observations of the K5
III hybrid star Gamma Dra. These data will also allow a detailed
comparison of its spectrum and the thermodynamic properties of its outer
atmosphere with those of the cooler M giant and supergiant stars Gamma
Cru and Alpha Ori, observed during previous cycles. We shall check for
variations in the C II downflow discovered in the SAO observations and
search for evidence of systematic flows in other emission lines. We
shall make detailed comparisons of the chromospheric emission lines and
wind signatures in the UV spectra of two stars of the same spectral
class, where one is a hybrid and one is not. We shall search for
evidence of shocks and/or propagating waves in the line variations
predicted by our recent calculations. We will also determine the
variation of wind velocity with height using semi-empirical non-LTE
models assuming spherical symmetry, search for evidence of circumstellar
and interstellar absorptions on resonance lines of O I, Fe II, and Mg
II, and compare the short-wavelength continuum measured in this star
with that detected in observations of Gamma Dra, Gamma Cru and Alpha
Ori.
Title: MG II H and K Profiles in Luminous, Cool Stars
Authors: Robinson, R. D.; Carpenter, K. G.
Affiliation: AA(CSC/GHRS), AB(NASA/GSFC)
Publication: American Astronomical Society, 182nd AAS Meeting,
\#46.19; Bulletin of the American Astronomical
Society, Vol. 25, p.877
Publication Date: 05/1993
Origin: AAS
Abstract Copyright: (c) 1993: American Astronomical Society
Bibliographic Code: 1993BAAS...25..877R
Abstract
As part of an investigation of the velocity fields in the atmospheres of
cool, luminous stars we used the Goddard High Resolution Spectrograph
(GHRS) aboard the Hubble Space Telescope to obtain a high resolution
spectrum of the Mg II h and k lines in the M supergiant alpha Ori. These
strong, centrally reversed emission lines have been well studied by the
IUE. While the h line in alpha Ori has nearly equal intensity in the red
and blue peaks, the blue peak of the k line is always much weaker than
the red peak. This asymmetry is normally explained as resulting from
absorption by Fe I and Mn I in the circumstellar shell. An examination
of the GHRS spectrum, however, reveals that the asymmetry results from a
velocity shift between the emission wings and the central absorption
core of the line. Further, while the central absorption profiles for the
h and k lines agree very well when plotted on a velocity scale, the
centroid of the k line emission wings was observed to be redshifted by
approximately 23 km/s with respect to that of the h line. Examination of
other high resolution GHRS observations of Mg II showed a similar,
though less pronounced, relative redshift of the k line centroid on the
normal M giant gamma Cru and the hybrid K giant gamma Dra. To date, no
concrete model has been proposed to explain these shifts. Examining well
exposed, high resolution IUE observations of alpha Ori shows a close
agreement with the GHRS results. This gives us confidence that we can
use IUE spectra to study the relative shapes and velocities of the Mg II
h and k lines and we are currently involved in a program to use the IUE
archive to quantify the behavior of the Mg II h and k profiles as a
function of luminosity and spectral type for luminous, cool stars. The
results of this program will be presented.
Title: A Search for CO Absorption Bands in IUE Spectra of
Cool Stars
Authors: Gessner, S.; Carpenter, K.; Robinson, R.
Affiliation: AA(USRA), AB(NASA-GSFC), AC(CSC)
Publication: American Astronomical Society, 182nd AAS Meeting,
\#46.12; Bulletin of the American Astronomical
Society, Vol. 25, p.875
Publication Date: 05/1993
Origin: AAS
Abstract Copyright: (c) 1993: American Astronomical Society
Bibliographic Code: 1993BAAS...25..875G
Abstract
Observations of the red supergiant (M2 Iab) alpha Ori with the Goddard
High Resolution Spectrograph (GHRS) onboard the Hubble Space Telescope
(HST) have provided an unambiguous detection of a far-UV continuum on
which are superposed strong molecular absorption bands (Carpenter 1991,
ASP Conf. Ser. 26, p. 17). The continuum is formed in the stellar
chromosphere. The absorption bands, which appear in the 1300 - 1600
Angstroms spectral region, have been identified with the (n,0) bands
(n=0,...,8) of the 4th-positive A-X system of CO and are likely formed
in the circumstellar shell. Comparison of these GHRS data with archival
IUE spectra indicates that both the continuum and the CO absorption
features can be seen with IUE, especially if multiple IUE spectra,
reduced with the post-1981 IUESIPS extraction procedure (i.e., with an
oversampling slit), are carefully co-added to increase the
signal-to-noise over that obtainable with a single spectrum. We have
therefore begun a program, utilizing both new and archival IUE spectra,
to survey other cool, low-gravity stars for the presence of these two
new chromospheric and circumstellar shell diagnostics. We hope to
identify promising targets for examination with HST spectrographs at the
higher resolution and signal-to-noise needed for quantitative analysis.
The initial results of this IUE survey are presented here.
Title: GHRS Observations of the M-giant gamma CRU
Authors: Carpenter, K.; Robinson, R.; Gessner, S.
Affiliation: AA(NASA-GSFC), AB(CSC), AC(USRA)
Publication: American Astronomical Society, 182nd AAS Meeting,
\#46.13; Bulletin of the American Astronomical
Society, Vol. 25, p.875
Publication Date: 05/1993
Origin: AAS
Abstract Copyright: (c) 1993: American Astronomical Society
Bibliographic Code: 1993BAAS...25..875C
Abstract
The Goddard High Resolution Spectrograph (GHRS) on the Hubble Space
Telescope has been used to obtain medium (R=20,000) and high (R=85,000)
resolution UV spectra of chromospheric emission features for the M3.4
III star gamma Cru. Large Science Aperture (LSA), medium resolution
spectra were obtained to survey the 1980 - 2200 Angstroms region with
good signal-to-noise. Small Science Aperture (SSA) G270M and Echelle-B
spectra of selected longer wavelength regions were obtained to allow the
measurement of velocity flows and turbulence for a variety of ions,
including C II, Fe II, Co II, Si I/II, Ni II, Mn II, and Mg II. Gaussian
fits to the optically thin C II (UV 0.01) intercombination lines and
fluorescently-excited lines of Co II, Ni II, Fe II, and Si I indicate
average turbulent velocities (Doppler FWHM) of 30.2 and 28.6 km/s,
respectively. For comparison, the C II turbulent velocity previously
measured for the K5 giant alpha Tau is ~ 24 km/s. The measured radial
velocities of the fluorescent lines average 21.5 km/s, which places them
basically at rest relative to the radial velocity of the star (21 km/s),
while the C II lines average 23.1 km/s, a modest inflow of a couple of
km/s. A subset of the collisionally-excited Fe II emission lines show an
average radial velocity of 22.6 km/s, also a very modest inflow, at
best. The stronger Fe II lines exhibit a more complex profile which
consists of a broad emission line with an ~ 40 km/s FWHM, on which are
superposed two absorption components. The stronger component appears at
relatively low radial velocity (in the 7 - 15 km/s range) in each line,
with a mean value over the sample of ~ 10.5 km/s, while the weaker
component appears at relatively high radial velocity in each line (in
the range from 25 to 34 km/s), with a mean value of ~ 31.3 km/s. The
first represents an outflow of about 10 km/s, while the second an inflow
of about 10 km/s. The Mg II h and k emission lines also show the
dual-absorption structure seen in the Fe II lines. However, both the
emission and absorption components in the k-line are red-shifted by 7 to
9.5 km/s, relative to their equivalent components in the h-line.
Title: Observations of 3C 273 with the Goddard High
Resolution Spectrograph on the Hubble Space
Telescope
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.;
Boggess, E. A.; Carpenter, K. G.; Ebbets, D. C.;
Hutchings, J. B.; Jura, M.; Leckrone, D. S.;
Linsky, J. L.; Maran, S. P.; Savage, B. D.;
Smith, A. M.; Trafton, L. M.; Walter, F. M.;
Weymann, R. J.; Snow, M.; Randall, C. E.;
Lindler, D. J.; Shore, S. N.; Morris, S. L.;
Gilliland, R. L.; Lu, L.; Robinson, R. D.
Affiliation: AA(Colorado Univ., Boulder), AB(NASA, Goddard Space
Flight Center, Greenbelt, MD), AC(California Univ.,
La Jolla), AD(NASA, Goddard Space Flight Center,
Greenbelt, MD), AE(NASA, Goddard Space Flight
Center, Greenbelt, MD), AF(Ball Aerospace Systems
Group, Boulder, CO), AG(Dominion Astrophysical
Observatory, Victoria, Canada), AH(California Univ.,
Los Angeles), AI(NASA, Goddard Space Flight Center,
Greenbelt, MD), AJ(Joint Inst. for Laboratory
Astrophysics; NIST, Quantum Physics Div., Boulder,
CO)
Publication: Astronomical Journal (ISSN 0004-6256), vol. 105, no.
3, p. 831-846.
Publication Date: 03/1993
Category: Astronomy
Origin: STI
NASA/STI Keywords: ABSORPTION SPECTRA, HUBBLE SPACE TELESCOPE, LINE
SPECTRA, QUASARS, DATA REDUCTION, IUE, SPECTROGRAPHS
DOI: 10.1086/116475
Bibliographic Code: 1993AJ....105..831B
Abstract
The observations of the quasar 3C 273 taken with the Goddard High
Resolution Spectrograph in 1991 February are presented here. We have
included both the reduced raw data, and smoothed and deconvolved
spectra. Also, a list of observed absorption lines is presented. The
data comprise 11 spectra, including one low resolution and 10 medium
resolution observations. The wavelength region covered ranged from about
1150 to 2820 A, but was not all inclusive. The procedures used to obtain
and reduce the data, including corrections for fixed pattern noise,
compensation for the effects of spherical aberration in the HST primary
mirror, and objective detection of weak absorption lines, are described.
We also have included a short discussion on the detection of galactic Ni
II and Virgo cluster metal lines.
Title: Atomic data needs for the analysis of the
ultraviolet spectrum of cool stars.
Authors: Carpenter, K. G.
Publication: Phys. Scr. T, Vol. T47, p. 139 - 142
Publication Date: 00/1993
Origin: ARI
ARI Keywords: Cool Stars: UV Spectra
Bibliographic Code: 1993PhST...47..139C
Abstract
A brief introduction to the UV spectra of cool stars is given, followed
by a review of astronomical observatories and instruments which are
capable of acquiring UV spectral data on cool stars. Examples of
observational data are presented, along with a description of typical
analysis performed on such data. The basic atomic data needed to perform
these analysis are summarized, with the most important UV multiples or
transitions of the most relevant ions identified.
Title: CO Molecular Absorption in Far-UV Spectra of Cool
Stars
Authors: Carpenter, Kenneth G.
Publication: IUE Proposal ID \#COPKC
Publication Date: 00/1993
Origin: IUE
Bibliographic Code: 1993iue..prop.4498C
Abstract
We propose a far-UV survey of cool giant and supergiant stars to search
for evidence of circumstellar absorption by the CO molecule. This survey
is motivated by the discovery of a far-UV continuum and superposed
circumstellar CO absorption in a spectrum of alpha Ori (M2 Iab) obtained
with HST and the subsequent demonstration that IUE is capable of
detecting these bands. These bands are an excellent probe of the
circumstellar regions of such stars, and provide diagnostics of layers
not well sampled by other techniques. Where possible, very rough
estimates of the conditions in the regions represented by the CO
absorption will be obtained on the basis of these IUE data. The results
of this survey will then be used to select targets /individual bands for
observation at higher resolution with the GHRS/HST to allow detailed
comparison with models and more precise determinations of temperatures
and column densities in the circumstellar environment of these stars.
Title: Observations of a Flare on AU MIC
Authors: Robinson, R. D.; Carpenter, K. G.; Woodgate, B. E.
Affiliation: AA(CSC), AB(NASA/GSFC), AC(NASA/GSFC)
Publication: American Astronomical Society, 181st AAS Meeting,
\#51.04; Bulletin of the American Astronomical
Society, Vol. 24, p.1206
Publication Date: 12/1992
Origin: AAS
Abstract Copyright: (c) 1992: American Astronomical Society
Bibliographic Code: 1992BAAS...24.1206R
Abstract
We report the results of a coordinated observing campaign of the active
dMe flare star AU Mic, carried out on 1992 Sept 9. Participating
instruments include the HST and IUE satellites and the 3.9m
Anglo-Australian Telescope. During this campaign a long duration, 1.5
mag (U band) flare was detected, with the maximum phase observed
simultaneously with the IUE and AAT and the decay phase monitored by all
three instruments. The AAT observations consisted of a time series of
CCD exposures covering the wavelength range 3650-4450 Angstroms and
having a temporal resolution of 6 seconds. The impulsive phase lasted
for about 1 minute and was therefore well resolved by these
observations. The flare showed pronounced broadening of the Balmer
series, with the Balmer line fluxes increasing with the continuum during
the impulsive phase but having a much longer decay time. A pronounced
HeII (4026 Angstroms ) emission was seen during the flare, with some
indication that this line increased in absorption strength about 30
seconds before the continuum increase. The CaII H and K lines decreased
in strength during the impulsive and early decay phase of the event, but
recovered during the later decay phase. A low resolution LWP exposure
was taken by the IUE during the peak of the flare. Combining this with
the optical data gives an almost complete coverage of the flare spectrum
from 2200 to 4500 Angstroms. We discuss the implications of these
observations in relation to current flare models.
Title: The Search for Acoustically-Driven Mass-Loss in
Evolved Stars
Authors: Stencel, R. E.; Brown, A.; Carpenter, K. G.;
Cuntz, M.; Judge, P.
Affiliation: AA(Univs.Colorado, Denver & Michigan), AB(JILA,
Univ.Colorado), AC(NASA), AD(HAO), AE(HAO)
Publication: American Astronomical Society, 181st AAS Meeting,
\#36.03; Bulletin of the American Astronomical
Society, Vol. 24, p.1175
Publication Date: 12/1992
Origin: AAS
Abstract Copyright: (c) 1992: American Astronomical Society
Bibliographic Code: 1992BAAS...24.1175S
Abstract
Recent ab-initio calculations of stochastic stellar wind models by Cuntz
(1992 in Cool Stars VII, ASP Conf. Ser. 26, p.383) have proven
remarkably robust in predicting observed chromospheric flow patterns
including possible variabilities with time in selected cool, evolved
stars. The calculations solve the equations of hydrodynamics using the
method of characteristics and assume: (i) saw-tooth shock wave profiles,
and (ii) wave periods were changed stochastically while keeping the wave
amplitudes constant (see Cuntz 1990 Ap.J. 349, p.141). Among the results
of fitting chromospheric flow velocities is the implication that the
permitted range of acoustic wave periods for a given star is
constrained. We made use of the IUE satellite during August and
September 1992 to repeatedly observe two stars, the yellow giant
Aldebaran (K5 III) and the red supergiant, Betelgeuse (M2 Iab), in order
to sample variations in their atmospheres on timescales of ~ 10(4) to ~
10(6) seconds, which bracket the predicted mean acoustic wave periods
for these objects. In particular, we obtained deep exposures in order to
measure density-sensitive line ratios within the C II] intercombination
features near 2325A (cf. Lennon et al. 1985 Ap.J. 294, p.200) to test
the hypothesis that density fluctuations could be measured as a
consequence of these acoustic waves. The results of these observations
will be presented and discussed in terms of the number and amplitude of
acoustic waves contributing to chromospheric heating and mass loss from
these stars, as well as the wave origins in the evolving oscillatory
structure of these stellar interiors. We are pleased to acknowledge
IUE--NASA grant NAG5-2103 for partial support of this effort.
Title: Detection of a proton beam during the impulsive
phase of a stellar flare
Authors: Woodgate, Bruce E.; Robinson, Richard D.;
Carpenter, Kenneth G.; Maran, Stephen P.;
Shore, Steven N.
Affiliation: AA(NASA, Goddard Space Flight Center, Greenbelt,
MD), AB(Computer Sciences Corp.; NASA, Goddard Space
Flight Center, Greenbelt, MD), AC(NASA, Goddard
Space Flight Center, Greenbelt, MD), AD(NASA,
Goddard Space Flight Center, Greenbelt, MD),
AE(Computer Sciences Corp.; NASA, Goddard Space
Flight Center, Greenbelt, MD)
Publication: Astrophysical Journal, Part 2 - Letters (ISSN
0004-637X), vol. 397, no. 2, p. L95-L98.
Publication Date: 10/1992
Category: Astrophysics
Origin: STI
NASA/STI Keywords: LYMAN ALPHA RADIATION, PROTON BEAMS, STELLAR
ACTIVITY, STELLAR FLARES, DATA REDUCTION, ELECTRON
BEAMS, RED DWARF STARS
DOI: 10.1086/186553
Bibliographic Code: 1992ApJ...397L..95W
Abstract
A transient event consistent with the predicted temporal and spectral
signatures of an energetic proton beam was detected in the impulsive
phase of a small flare on the red dwarf star AU Microscopii. It
consisted of a prominent increase in the flux in the red wing of
Lyman-alpha near 1223 A, simultaneously with the peak of a flare
observed in the 1206 A transition region line of Si III. The probability
that the red wing event was a chance fluctuation is one chance in 2.5 x
10 exp 4. This observation represents a confirmation of the prediction
by Orrall and Zirker (1976) in which downstreaming protons accelerated
during the impulsive phase of a flare charge exchange with ambient
neutral hydrogen and emit Lyman-alpha radiation from 1 to 15 A redward
of line center.
Title: A wide bandwidth, dynamic hysteresis model for
magnetization in soft ferrites
Authors: Carpenter, K. H.; Warren, S.
Publication: IEEE Transactions on Magnetics, vol. 28, issue 5,
pp. 2037-2041
Publication Date: 09/1992
Origin: CROSSREF
DOI: 10.1109/20.179395
Bibliographic Code: 1992ITM....28.2037C
Abstract
Not Available
Title: The Ultraviolet Photospheric Spectrum of Alpha
Orionis
Authors: Wahlgren, G. M.; Robinson, R. D.; Carpenter, K. G.
Publication: American Astronomical Society, 181st AAS Meeting,
\#100.10; Bulletin of the American Astronomical
Society, Vol. 24, p.1280
Publication Date: 09/1992
Origin: ADS
Bibliographic Code: 1992BAAS...24.1280W
Abstract
Not Available
Title: Plasma Flows in the Outer Atmosphere of alpha Ori
Authors: Carpenter, K.; Robinson, R.; Wahlgren, G.;
Brandt, J.; Linsky, J.; Ebbets, D.; Weymann, R.
Publication: American Astronomical Society, 181st AAS Meeting,
\#51.11; Bulletin of the American Astronomical
Society, Vol. 24, p.1207
Publication Date: 09/1992
Origin: ADS
Bibliographic Code: 1992BAAS...24.1207C
Abstract
Not Available
Title: Physical Conditions and Velocity Structures in the
Red Giant Winds in the Binaries CI CYG and EG and --
Cycle 2
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#3934
Publication Date: 07/1992
Origin: HST
Keywords: HST Proposal ID \#3934
Bibliographic Code: 1992hst..prop.3934C
Abstract
This proposal represents a two pronged attack aimed at understanding the
detailed chracteristics of red giant winds in binary star systems. Red
giant winds can provide the most massive, sustained form of mass
transfer in binaries. The symbiotic and related stars, which contain red
giant and hot companion stars, permit line of sight studies through a
range of red giant atmospheric heights. The goal of this work is to
attempt to define both the mechanism of rapid mass loss in red giant
stars and the details of mass transfer to the companion stars. Such
results can provide important constraints for both stellar and binary
evolution theories. In each case we expect to derive density and
temperature values for the red giant wind region and compare this to the
present understanding of single star conditions where low temperature,
dust and molecule forming, circumstellar envelopes prevail.
Title: Revised Faint Target/bright Neighbor Test
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#3416
Publication Date: 07/1992
Origin: HST
Keywords: HST Proposal ID \#3416 CALIBRATION
Bibliographic Code: 1992hst..prop.3416C
Abstract
Verify capability of HRS to detect weak emission despite immediate
proximity of a bright source. Measure near-angle scattering into HRS
apertures from adjacent bright source. Revised July 24, 1991 by DCE to
complete sequences lost during April 91 execution when carrousel safed.
Revised March 1992 BY DCE for SSA G160M 1300 only
Title: Dinosaur Systematics
Authors: Carpenter, Kenneth; Currie, Philip J.
Affiliation: AA(Denver Museum of Natural History),AB(Tyrrell
Museum of Palaeontology, Alberta)
Publication: Dinosaur Systematics, Edited by Kenneth Carpenter
and Philip J. Currie, pp. 334. ISBN 0521438101.
Cambridge, UK: Cambridge University Press, July
1992.
Publication Date: 07/1992
Origin: CUP
Bibliographic Code: 1992disy.book.....C
Abstract
In recent years dinosaurs have captured the attention of the public at
an unprecedented level. At the heart of this resurgence in popular
interest is an increased level of research activity, much of which is
innovative in the field of paleontology. For instance, whereas earlier
paleontological studies emphasized basic morphologic description and
taxonomic classification, modern studies attempt to examine the role and
nature of dinosaurs as living animals. More than ever before, we
understand how these extinct species functioned, behaved, interacted
with each other and the environment, and evolved. Nevertheless, these
studies rely on certain basic building blocks of knowledge, including
facts about dinosaur anatomy and taxonomic relationships. One of the
purposes of this volume is to unravel some of the problems surrounding
dinosaur systematics and to increase our understanding of dinosaurs as a
biological species. Dinosaur Systematics presents a current overview
of dinosaur systematics using various examples to explore what is a
species in a dinosaur, what separates genders in dinosaurs, what
morphological changes occur with maturation of a species, and what
morphological variations occur within a species.
Title: Detection of a Proton Beam during the Impulsive
phase of a Stellar Flare
Authors: Woodgate, B. E.; Robinson, R. D.; Carpenter, K. G.;
Maran, S. P.; Shore, S.
Affiliation: AA(NASA/GSFC), AB(CSC), AC(NASA/GSFC),
AD(NASA/GSFC), AE(CSC)
Publication: American Astronomical Society, 180th AAS Meeting,
\#30.10; Bulletin of the American Astronomical
Society, Vol. 24, p.777
Publication Date: 05/1992
Origin: AAS
Abstract Copyright: (c) 1992: American Astronomical Society
Bibliographic Code: 1992BAAS...24..777W
Abstract
We present evidence for the detection of a proton beam during the
impulsive phase of a flare on the Dme star AU Microscopii. At 1991 Sept
3 04h 56m 10s UT, the Goddard High Resolution Spectrograph on the Hubble
Space Telescope observed an increase in the flux in the red wing of the
hydrogen Lyman alpha line at 1223A, unaccompanied by an increase in the
blue wing, simultaneously with an increase in the flux of the SiIII
1206A transition region line. The 1223A flux increase was 2.2 x 1027
ergs s-1 A-1, with 3s duration. The chance probability of the
observation is 1 in 105. This effect was predicted by Orrall and Zirker
(1976), as a downstreaming beam of protons charge exchanging with
ambient neutral hydrogen and emitting Lyman alpha radiation at the
downstreaming velocity. The energy in the beam is estimated as 7 x 1029
ergs s-1.
Title: A Search for CO Molecular Absorption in Far-UV
Spectra of Cool Stars
Authors: Carpenter, Kenneth G.
Publication: IUE Proposal ID \#COOKC
Publication Date: 00/1992
Origin: IUE
Bibliographic Code: 1992iue..prop.4214C
Abstract
We propose a far-UV survey of cool giant and supergiant stars to search
for evidence of circumstellar absorption by the CO molecule. This survey
is motivated by the discovery of a far-UV continuum and superposed
circumstellar CO absorption in a spectrum of alpha Ori (M2 lab) obtained
with HST and the subsequent demonstration that IUE is capable of
detecting these bands. These bands are an excellent probe of the
circumstellar regions of such stars, and provide diagnostics of layers
not well sampled by other techniques. Where possible, very rough
estimates of the conditions in the regions represented by the CO
absorption will be obtained on the basis of these IUE data. The results
of this survey will then be used to select targets/individual bands for
observation at higher resolution with the GHRS/HST to allow detailed
comparison with models and more precise determinations of temperatures
and column densities in the circumstellar environment of these stars.
Title: Simultaneous IUE/HST-GHRS Observations of AU MIC
Authors: Carpenter, Kenneth G.
Publication: IUE Proposal ID \#AUOKC
Publication Date: 00/1992
Origin: IUE
Bibliographic Code: 1992iue..prop.4212C
Abstract
We propose to monitor the early dwarf-M flare star and BY Dra variable
AU Mic over two IUE shifts approximately centered on the time of HST
observations with the GHRS. The GHRS observations are part of a Cycle 1
HST GO program that is to be reexecuted in late summer of 1992, due to
an intermittent HST instrument failure during the initial execution of
the HST program in September 1991. The GHRS observations cover a single,
very narrow range of wavelengths (36 A) containing Lyman-alpha, Si III
1206 A, and O V 1218 A. They will be obtained at very high time
resolution (0.4 sec/integration) and are designed to look for evidence
of proton downflow during the impulsive phase of a flare. We request
simultaneous IUE observations to place the HST observations in a broader
context, which will include a wider variety of chromospheric and
transition region lines and their behavior over a 16 hour period
approximately centered on the time of the GHRS observations. IUE data is
critically needed during flare detections by HST, so that the radiative
losses in the UV can be estimated and compared to the energy carried in
the proton downflow, in order to evaluate the importance of this energy
source to the flare.
Title: Zeta-Aurigae Type Binaries
Authors: Carpenter, K. G.
Publication: Evolutionary Processes in Interacting Binary Stars.
Proceedings of the 151st. Symposium of the
International Astronomical Union, held in Cordoba,
Argentina, August 5-9, 1991. Editors, Y. Kondo, R.
F. Sistero, R. S. Polidan; Publisher, Kluwer
Academic Publishers, Dordrecht, Boston, MA, 1992. LC
\# QB821 .I62 1991. ISBN: 0-7923-1731-9. P. 51, 1992
Publication Date: 00/1992
Origin: ADS
Bibliographic Code: 1992IAUS..151...51C
Abstract
Not Available
Title: Chromospheres and winds of cool stars
Authors: Carpenter, K. G.
Publication: Highlights of Astronomy, Vol. 9, p.477
Publication Date: 00/1992
Origin: ADS
Bibliographic Code: 1992HiA.....9..477C
Abstract
Not Available
Title: Detection of a Proton Beam during the Impulsive
Phase of a Stellar Flare
Authors: Robinson, R. D.; Woodgate, B. E.; Carpenter, K. G.;
Maran, S. P.; Shore, S. N.
Publication: Science with the Hubble Space Telescope, Proceedings
of a ST-ECF/STScI Workshop held in Chia Laguna,
Sardinia, Italy 29 June - 7 July 1992. ESO
Conference and Workshop Proceedings, No. 44. Edited
by Piero Benvenuti and Ethan J. Schreier. Garching
near Munich: European Southern Observatory, 1992.,
p.447
Publication Date: 00/1992
Origin: ADS
Bibliographic Code: 1992ESOC...44..447R
Abstract
Not Available
Title: The Chromosphere and Circumstellar Shell of alpha
Orionis as Observed with the Goddard High Resolution
Spectrograph
Authors: Carpenter, K. G.; Robinson, R. D.; Wahlgren, G. M.;
Linsky, J. L.; Brown, A.
Publication: Science with the Hubble Space Telescope, Proceedings
of a ST-ECF/STScI Workshop held in Chia Laguna,
Sardinia, Italy 29 June - 7 July 1992. ESO
Conference and Workshop Proceedings, No. 44. Edited
by Piero Benvenuti and Ethan J. Schreier. Garching
near Munich: European Southern Observatory, 1992.,
p.387
Publication Date: 00/1992
Origin: ADS
Bibliographic Code: 1992ESOC...44..387C
Abstract
Not Available
Title: A Search for Short-Timescale Variations in the
Chromosphere; UV Spectrum of the M-Giant Gamma
Crucis
Authors: Cheng, K.-P.; Carpenter, K. G.
Publication: Cool stars, stellar systems, and the sun,
Proceedings of the 7th Cambridge Workshop, ASP
Conference Series (ASP: San Francisco), vol. 26, p.
43.
Publication Date: 00/1992
Origin: ADS
Bibliographic Code: 1992ASPC...26...43C
Abstract
Not Available
Title: Molecular Absorption in the UV Spectrum of A ORI
Authors: Wahlgren, G. M.; Robinson, R. D.; Carpenter, K. G.
Publication: Cool stars, stellar systems, and the sun,
Proceedings of the 7th Cambridge Workshop, ASP
Conference Series (ASP: San Francisco), vol. 26, p.
37.
Publication Date: 00/1992
Origin: ADS
Bibliographic Code: 1992ASPC...26...37W
Abstract
Not Available
Title: HST Observations of the Flare Star AU MIC
Authors: Robinson, R. D.; Shore, S. N.; Carpenter, K. G.;
Woodgate, B. E.; Maran, S. P.; Brandt, J. C.;
Kundu, M. R.; White, S. M.; Linsky, J. L.;
Walter, F. M.
Publication: Cool stars, stellar systems, and the sun,
Proceedings of the 7th Cambridge Workshop, ASP
Conference Series (ASP: San Francisco), vol. 26, p.
31.
Publication Date: 00/1992
Origin: ADS
Bibliographic Code: 1992ASPC...26...31R
Abstract
Not Available
Title: Late-Type Stars (Invited Review)
Authors: Carpenter, K. G.
Publication: Cool stars, stellar systems, and the sun,
Proceedings of the 7th Cambridge Workshop, ASP
Conference Series (ASP: San Francisco), vol. 26, p.
17.
Publication Date: 00/1992
Origin: ADS
Bibliographic Code: 1992ASPC...26...17C
Abstract
Not Available
Title: SI II emission line diagnostics
Authors: Judge, P. G.; Carpenter, K. G.; Harper, G. M.
Affiliation: AA(High Altitude Observatory, Boulder, CO), AB(NASA,
Goddard Space Flight Center, Greenbelt, MD),
AC(Oxford, University, England)
Publication: Royal Astronomical Society, Monthly Notices (ISSN
0035-8711), vol. 253, Nov. 1, 1991, p. 123-128.
Research supported by SERC.
Publication Date: 11/1991
Category: Astrophysics
Origin: STI
NASA/STI Keywords: EMISSION SPECTRA, K STARS, SILICON, SPACEBORNE
ASTRONOMY, ULTRAVIOLET EMISSION, ELECTRON
TRANSITIONS, HUBBLE SPACE TELESCOPE, IUE, LINE
SPECTRA, RADIATIVE TRANSFER
Bibliographic Code: 1991MNRAS.253..123J
Abstract
The present study compares ratios of Si II UV emission lines in a
variety of objects with computations based on recently published
collisional data of Dufton and Kingston (1991). A high-quality spectrum
of Alpha Tau (K5 III) obtained by Carpenter et al. (1991) is analyzed
using the G270M mode of the GHRS on the HST, in addition to
high-dispersion data from Skylab and IUE. Agreement between observation
and theory is satisfactory for most lines. A blend with a line of Ni II
accounts partially for the discrepancies and solves a problem with
semiforbidden S II emission measures. Disagreement exists between
certain observed flux ratios and computed values using recent atomic
data for the intersystem lines. The discrepancy is most significant for
Alpha Tau. The computed atomic collision strengths within the
intersystem multiplet itself are argued as a possible cause of the
discrepancy.
Title: A differential equation approach to minor loops in
the Jiles-Atherton hysteresis model
Authors: Carpenter, K. H.
Publication: IEEE Transactions on Magnetics, vol. 27, issue 6,
pp. 4404-4406
Publication Date: 11/1991
Origin: CROSSREF
DOI: 10.1109/20.278655
Bibliographic Code: 1991ITM....27.4404C
Abstract
Not Available
Title: Molecular Absorption in the Ultraviolet Spectrum of
Alpha Ori
Authors: Wahlgren, G. M.; Robinson, R. D.; Carpenter, K. G.
Publication: Bulletin of the American Astronomical Society, Vol.
23, p.1386
Publication Date: 09/1991
Origin: ADS
Bibliographic Code: 1991BAAS...23.1386W
Abstract
Not Available
Title: Time Resolved Observations of the Lyman-Alpha Region
in AU Mic with the Goddard High Resolution
Spectrograph
Authors: Woodgate, B. E.; Maran, S. P.; Carpenter, K. G.;
Robinson, R. D.; Shore, S. N.; Linsky, J. L.;
Byrne, P. B.; Kundu, M. R.
Publication: Bulletin of the American Astronomical Society, Vol.
23, p.1383
Publication Date: 09/1991
Origin: ADS
Bibliographic Code: 1991BAAS...23.1383W
Abstract
Not Available
Title: Coordinated IUE/HST Observations of the Flare Star
AU mic: Results from IUE
Authors: Carpenter, K. G.; Maran, S. P.; Brown, A.;
Linsky, J. L.; Robinson, R. D.; Byrne, P. B.;
Judge, P. G.
Publication: Bulletin of the American Astronomical Society, Vol.
23, p.1383
Publication Date: 09/1991
Origin: ADS
Bibliographic Code: 1991BAAS...23.1383C
Abstract
Not Available
Title: An Investigation of the Flare Star AU Mic with the
Goddard High Resolution Spectrograph on the Hubble
Space Telescope
Authors: Maran, S. P.; Woodgate, B. E.; Carpenter, K. G.;
Robinson, R. D.; Shore, S. N.; Linsky, J. L.;
Brown, A.; Byrne, P. B.; Kundu, M. R.; White, S.;
Brandt, J. C.; Shine, R. A.; Walter, F. M.
Publication: Bulletin of the American Astronomical Society, Vol.
23, p.1382
Publication Date: 09/1991
Origin: ADS
Bibliographic Code: 1991BAAS...23.1382M
Abstract
Not Available
Title: First results from the Goddard High-Resolution
Spectrograph - The chromosphere of Alpha Tauri
Authors: Carpenter, Kenneth G.; Robinson, Richard D.;
Wahlgren, Glenn M.; Ake, Thomas B.;
Ebbets, Dennis C.; Linsky, Jeffrey L.;
Brown, Alexander; Walter, Frederick M.
Affiliation: AA(NASA, Goddard Space Flight Center, Greenbelt,
MD), AB(NASA, Goddard Space Flight Center; Computer
Sciences Corp., Greenbelt, MD), AC(NASA, Goddard
Space Flight Center; Computer Sciences Corp.,
Greenbelt, MD), AD(NASA, Goddard Space Flight
Center; Computer Sciences Corp., Greenbelt, MD),
AE(Ball Aerospace Systems Group, Boulder, CO)
Publication: Astrophysical Journal, Part 2 - Letters (ISSN
0004-637X), vol. 377, Aug. 10, 1991, p. L45-L48.
Publication Date: 08/1991
Category: Astrophysics
Origin: STI
NASA/STI Keywords: CHROMOSPHERE, HUBBLE SPACE TELESCOPE, K STARS, LATE
STARS, SPECTROGRAPHS, ULTRAVIOLET SPECTRA, EMISSION
SPECTRA, HIGH RESOLUTION, LINE SPECTRA
DOI: 10.1086/186113
Bibliographic Code: 1991ApJ...377L..45C
Abstract
The K5 III star Alpha Tau was observed with the Goddard High Resolution
Spectrograph on November 27, 1990 as part of the Science Assessment
Program for the HST. The spectra show intersystem and permitted
chromospheric emission lines of semiforbidden C II and Si II, Fe II, Fe
I, Ni II, and Co II. Resolved profiles of the semiforbidden C II lines
indicate a complex chromospheric turbulent velocity distribution with
mean value of roughly 24 km/s, while their observed wavelengths indicate
a 4 km/s downflow of the semiforbidden C II plasma. Twenty-five new
emission lines have been found in the 2320-2370 A region, 17 of which
have been identified with the aid of Skylab data obtained above the
solar limb, including four lines from Co II (UV 8) and an Fe I (UV 12)
line.
Title: Physical Conditions and Velocity Structures in the
Red Giant Winds in the Binaries CI CYG and EG and --
Repeat for HOPR\#67
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#4251
Publication Date: 07/1991
Origin: HST
Keywords: HST Proposal ID \#4251 STELLAR ASTROPHYSICS
Bibliographic Code: 1991hst..prop.4251C
Abstract
This proposal represents a two pronged attack aimed at understanding the
detailed chracteristics of red giant winds in binary star systems. Red
giant winds can provide the most massive, sustained form of mass
transfer in binaries. The symbiotic and related stars, which contain red
giant and hot companion stars, permit line of sight studies through a
range of red giant atmospheric heights. The goal of this work is to
attempt to define both the mechanism of rapid mass loss in red giant
stars and the details of mass transfer to the companion stars. Such
results can provide important constraints for both stellar and binary
evolution theories. In each case we expect to derive density and
temperature values for the red giant wind region and compare this to the
present understanding of single star conditions where low temperature,
dust and molecule forming, circumstellar envelopes prevail. (Only EG And
observations are included in this file)
Title: Winds and Chromospheres of Cool Luminous Stars --
Cycle 1
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#3212
Publication Date: 07/1991
Origin: HST
Keywords: HST Proposal ID \#3212
Bibliographic Code: 1991hst..prop.3212C
Abstract
The goals of this program are to determine the physical characteristics
of the winds/chromospheres around cool luminous stars. GHRS observations
of the C II (UV 1) 1335 A and (UV 0.01) 2325 A multiplets will be used
along with observations of the C I lines near 1655 and 1994 A to
constrain the temperatures and densities in model chromospheres. The C
II (UV 0.01) lines will also be used to estimate the turbulence in these
chromospheres. The (confusing) far UV spectrum of the M supergiants will
be explored with the GHRS. GHRS observations of Fe II lines will be used
to study the dependence of the wind velocity on radial distance above
the photosphere. High quality Fe II and Mg II profiles will be acquired
to search for discrete velocity features and the presence of
circumstellar absorption within the profiles. The photospheric
absorption-line spectrum (2579-2675 A) of Arcturus will be observed in
the echelle mode. Medium resolution observations of Fe II and Mg II in
the dusty, very luminous star Mu Cep will provide information on the
effect of dust and very low gravity on the wind velocity field. *** this
file contains the Cycle 1 observations only ***
Title: Alpha Orionis GHRS Team Project -- Cycle 1
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#1199
Publication Date: 07/1991
Origin: HST
Keywords: HST Proposal ID \#1199
Bibliographic Code: 1991hst..prop.1199C
Abstract
The HRS will be used to obtain high signal/noise spectra of the 1980 -
3300 A spectral region of the M2 Iab supergiant Alpha Orionis. This full
wavelength region will be observed at medium resolution, while 3
selected wavelength regions will be observed in the echelle mode.
Exposure times have been chosen so that both the chromospheric emission
line spectrum and the photospheric continuum and absorption line
spectrum will be properly exposed. These observations will be combined
and published in atlas format. It is hoped that this atlas will provide
a standard against which high-resolution UV observations of other
late-type stars can be compared. Detailed analysis of these data are
planned by various IDT members.
Title: Physical Conditions and Velocity Structures in the
Red Giant Winds in the Binaries CI CYG and EG and --
Cycle 1
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#1198
Publication Date: 07/1991
Origin: HST
Keywords: HST Proposal ID \#1198
Bibliographic Code: 1991hst..prop.1198C
Abstract
This proposal represents a two pronged attack aimed at understanding the
detailed chracteristics of red giant winds in binary star systems. Red
giant winds can provide the most massive, sustained form of mass
transfer in binaries. The symbiotic and related stars, which contain red
giant and hot companion stars, permit line of sight studies through a
range of red giant atmospheric heights. The goal of this work is to
attempt to define both the mechanism of rapid mass loss in red giant
stars and the details of mass transfer to the companion stars. Such
results can provide important constraints for both stellar and binary
evolution theories. In each case we expect to derive density and
temperature values for the red giant wind region and compare this to the
present understanding of single star conditions where low temperature,
dust and molecule forming, circumstellar envelopes prevail.
Title: A differential equation approach to minor loops in
the Jiles-Atherton hysteresis model
Authors: Carpenter, K. H.
Affiliation: AA(Kansas State Univ., Manhattan.)
Publication: Unknown
Publication Date: 04/1991
Category: Physics (General)
Origin: STI
NASA/STI Keywords: DIFFERENTIAL EQUATIONS, FERROMAGNETIC MATERIALS,
HYSTERESIS, LOOPS, MAGNETIZATION, MATHEMATICAL
MODELS, REVISIONS
Bibliographic Code: 1991deam.rept.....C
Abstract
Jiles and Atherton, in a series of papers, present physically based
differential equations for magnetization in ferromagnetic materials.
However, if one directly solves their differential equations, the minor
loops obtained can have negative slopes, which is a non-physical
behavior. Only one of their papers gives a method for obtaining minor
loops, and the method does not use a differential equation, but requires
a priori knowledge of the loop turning points in order to obtain a scale
factor and offset which allow a portion of a major loop to serve as a
portion of a minor one. In this paper the reason for the failure of the
original differential equations to yield physical minor loops is
explained, and a modified solution for minor loops is presented which
retains the features of Jiles and Atherton's minor loops, but only
requires knowledge of the initial point on each portion of the loop to
obtain the solution. This yields a general differential equation
formulation for the Jiles-Atherton theory that can be used with circuit
simulations having arbitrary excitations and initial conditions for
ferromagnetic components.
Title: GHRS Spectroscopy of Cool Stars. II.
Authors: Brown, A.; Linsky, J.; Carpenter, K.; Robinson, R.;
Ebbets, D.
Publication: Bulletin of the American Astronomical Society, Vol.
23, p.910
Publication Date: 03/1991
Origin: ADS
Bibliographic Code: 1991BAAS...23R.910B
Abstract
Not Available
Title: GHRS Far-Ultraviolet Spectra of the Coronal Giant
Capella Binary
Authors: Linsky, J. L.; Brown, A.; Carpenter, K.;
Robinson, R.
Publication: Bulletin of the American Astronomical Society, Vol.
23, p.910
Publication Date: 03/1991
Origin: ADS
Bibliographic Code: 1991BAAS...23..910L
Abstract
Not Available
Title: GHRS Spectroscopy of Cool Stars. I.
Authors: Carpenter, K.; Robinson, R.; Ebbets, D.; Brown, A.;
Linsky, J.
Publication: Bulletin of the American Astronomical Society, Vol.
23, p.910
Publication Date: 03/1991
Origin: ADS
Bibliographic Code: 1991BAAS...23..910C
Abstract
Not Available
Title: Simultaneous IUE/HST-GHRS Observations of AU MIC
Authors: Carpenter, Kenneth G.
Publication: IUE Proposal ID \#FSLKC
Publication Date: 00/1991
Origin: IUE
Bibliographic Code: 1991iue..prop.3944C
Abstract
We propose to monitor the early dwarf-M flare star and BY Dra variable
AU Mic over a two day period centered on the time of HST observations
with the GHRS. The GHRS observations are part of the GHRS Investigation
Definition Teams's Guaranteed Time Observing (GTO) program and are
already approved. The GHRS observations cover a single, very narrow
range of wavelengths (1342 - 1378 A) and their prime purpose is to
detect and measure lines formed in the corona and in coronal flares,
such as Fe XXI 1354 A and Fe XII 1349 A, that are too weak to be
observed by IUE, along with a single transition region line (0 V) and
lines from one chromospheric ion (C 1). We request simultaneous IUE
observations to place the HST observations in a broader context, which
will include a wider variety of chromospheric and transition region
lines and their behavior over a 48 hour period approximately centered on
the time of the GHRS observations. The GHRS observations are to be
scheduled during HST Cycle 0, which (based on a December 1989 launch)
covers the period February 15 - July 15, 1990 and could occur during
either the 12th or 13th IUE observing episodes. This proposal is thus
for two years, but all the NASA and ESA shifts are required to be
contiguous and at a time which will overlap the HST observations.
Title: Ghrs/ Goddard High Resolution Spectroscopy
Chromospheric Emission Line Spectra of the Red Giant
Alpha-Tauri
Authors: Carpenter, K. G.; Robinson, R. D.; Ebbets, D. C.;
Brown, A.; Linsky, J. L.
Publication: The First Year of HST Observations. Proceedings of a
workshop held at the Space Telescope Science
Institute, Baltimore, Maryland, May 14-16, 1991.
Editors, A.L. Kinney, J.C. Blades; Publisher, Space
Telescope Science Institute, Baltimore, MD, 1991. LC
\# QB500.268 .F578 1991. ISBN: None. P.212, 1991
Publication Date: 00/1991
Origin: ADS
Bibliographic Code: 1991fyho.conf..212C
Abstract
Not Available
Title: GHRS / Goddard High Resolution Spectrograph / Far
Ultraviolet Spectra of Coronal and Noncoronal Stars
- Capella and Gamma-Draconis
Authors: Linsky, J. L.; Brown, A.; Carpenter, K. G.
Publication: The First Year of HST Observations. Proceedings of a
workshop held at the Space Telescope Science
Institute, Baltimore, Maryland, May 14-16, 1991.
Editors, A.L. Kinney, J.C. Blades; Publisher, Space
Telescope Science Institute, Baltimore, MD, 1991. LC
\# QB500.268 .F578 1991. ISBN: None. P. 70, 1991
Publication Date: 00/1991
Origin: ADS
Bibliographic Code: 1991fyho.conf...70L
Abstract
Not Available
Title: The First GHRS Spectra of a Cool Star: The
Chromosphere of Alpha Tau
Authors: Carpenter, K.; Robinson, R.; Ebbets, D.; Linsky, J.;
Walter, F.; Wahlgren, G.; Ake, T.
Publication: Bulletin of the American Astronomical Society, Vol.
22, p.1277
Publication Date: 09/1990
Origin: ADS
Bibliographic Code: 1990BAAS...22.1277C
Abstract
Not Available
Title: On the disappearance of OI in some high-luminosity
cool stars
Authors: Carpenter, K. G.; Norman, D.; Robinson, R.;
Fernandez-Villacanas, J. L.; Jordan, C.; Judge, P.
Publication: Evolution in Astrophysics: IUE Astronomy in the Era
of New Space Missions; proceedings of an
international conference held in Toulouse, France 29
May - 1 June 1990. Organised by European Space
Agency, National Aeronautics and Space
Administration, Science and Engineering Research
Council, Centre National d'Etudes Spatiales;
co-sponsored by Universite Paul Sabatier. Edited by
E.J. Rolfe. Paris, France: European Space Agency;
Noordwijk, Netherlands: Published by ESA
Publications Division, ESA SP-310, 1990., p.307
Publication Date: 08/1990
Origin: ADS
Bibliographic Code: 1990ESASP.310..307C
Abstract
Not Available
Title: Faint Target/bright Neighbor Test
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#1370
Publication Date: 07/1990
Origin: HST
Keywords: HST Proposal ID \#1370 CALIBRATION
Bibliographic Code: 1990hst..prop.1370C
Abstract
Verify capability of HRS to detect weak emission despite immediate
proximity of a bright source. Measure near-angle scattering into HRS
apertures from adjacent bright source. The test numbers indicate the
relative priorities of all HRS SV tests. All internal tests and all the
HRS external target acquisition tests must be run before this test. The
numbering of the remaining tests indicates our preferences, but slight
changes in their ordering are acceptable. Updated 8/24/89 to changed
COND ON 50-58... to COND IF on line 49 and add COND IF to line 54.
(PStanley)
Title: Intermediate/high Resolution Scattered Light/solar
Blind Characteristics
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#1362
Publication Date: 07/1990
Origin: HST
Keywords: HST Proposal ID \#1362 CALIBRATION
Bibliographic Code: 1990hst..prop.1362C
Abstract
THE PURPOSES OF THIS TEST ARE TO MEASURE WIDE ANGLE SCATTERED LIGHT AND
SOLAR BLIND CHARACTERISTICS OF THE INTERMEDIATE AND HIGH RESOLUTION GHRS
GRATING CONFIGURATIONS (G140M,G160M, G270M, ECH-A, AND ECH-B).
Title: Low Resolution Scattered Light/solar Blind
Characteristics
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#1361
Publication Date: 07/1990
Origin: HST
Keywords: HST Proposal ID \#1361 CALIBRATION
Bibliographic Code: 1990hst..prop.1361C
Abstract
The purposes of this test are to measure the wide angle scattered light
and solar blind characteristics of the low resolution (G140L) grating
configuration. The test numbers indicate the relative priorities of all
HRS SV tests. All internal tests and all the HRS external target
acquisition tests must be run before this test. Slight changes in the
position of this test within the later tests are acceptable.
Title: Winds of Cool Luminous Stars: Densities,
Temperatures, Geometric Extents, and Velocity
Structures -- Cycle 0
Authors: Carpenter, Kenneth
Publication: HST Proposal ID \#1195
Publication Date: 07/1990
Origin: HST
Keywords: HST Proposal ID \#1195
Bibliographic Code: 1990hst..prop.1195C
Abstract
The goals of this program are to determine the physical characteristics
of the winds/chromospheres around cool luminous stars. GHRS observations
of the C II (UV 1) 1335 A and (UV 0.01) 2325 A multiplets will be used
along with observations of the C I lines near 1655 and 1994 A to
constrain the temperatures and densities in model chromospheres. The C
II (UV 0.01) lines will also be used to estimate the turbulence in these
chromospheres. The (confusing) far UV spectrum of the M supergiants will
be explored with the GHRS. GHRS echelle observations of a set of Fe II
lines in the 2700 - 2800 A region will be used to study the dependence
of the wind velocity on radial distance above the photosphere. High
quality Mg II profiles will be acquired to search for discrete velocity
features and the presence of circumstellar absorption within the
profiles. The photospheric absorption-line spectrum (2579-2675 A) of
Arcturus will be observed in the echelle mode. Medium resolution
observations of Fe II and Mg II in the dusty, very luminous star Mu Cep
will provide information on the effect of dust and very low gravity on
the wind velocity field.
Title: Toward mapping the UV circumstellar shells of
late-type stars
Authors: Stencel, Robert E.; Judge, Philip G.;
Carpenter, Kenneth G.
Affiliation: AA(Colorado, University, Boulder), AB(Colorado,
University, Boulder), AC(NASA, Goddard Space Flight
Center, Greenbelt, MD)
Publication: IN: Cool stars, stellar systems, and the sun;
Proceedings of the 6th Cambridge Workshop, Seattle,
WA, Sept. 18-21, 1989 (A91-44876 19-90). San
Francisco, CA, Astronomical Society of the Pacific,
1990, p. 467-470.
Publication Date: 00/1990
Category: Astrophysics
Origin: STI
NASA/STI Keywords: LATE STARS, STELLAR ENVELOPES, ULTRAVIOLET
ASTRONOMY, IUE, STELLAR COLOR, STELLAR TEMPERATURE
Bibliographic Code: 1990ASPC....9..467S
Abstract
Detection of spatially resolved circumstellar matter surrounding
selected cool stars, using off-source observations made with the
International Ultraviolet Explorer satellite, is reported. The data
demonstrate that: (1) the instrumental scattered light profile of IUE
appears to depend on the ultraviolet color temperature of the star
observed, and (2) certain red stars show signal in excess of the
instrumental levels, at spatial offsets of 10 to 20 arc-seconds from the
star.
Title: Modeling the Ultraviolet Photospheric Spectrum of
Cool Giant Stars - Part Two - Gamma-Crucis
Authors: Wahlgren, G. M.; Carpenter, K. G.
Publication: Cambridge Workshop on Cool Stars, Stellar Systems,
and the Sun. Sixth Cambridge Workshop, 1989,
Editors, George Wallerstein; Publisher, Astronomical
Society of the Pacific, San Francisco, CA, 1990. LC
\# QB799 .C36 1989. ISBN: 0-937707-27-9. P. 67, 1990
Publication Date: 00/1990
Origin: ADS
Comment: ISBN: 0-937707-27-9
Bibliographic Code: 1990ASPC....9...67W
Abstract
Not Available
Title: Modeling the ultraviolet photospheric spectrum of
cool giant stars. II. Gamma Crucis.
Authors: Wahlgren, G. M.; Carpenter, K. G.
Publication: 6. Cambridge Workshop on Cool Stars, Stellar Systems
and the Sun, p. 65 - 69
Publication Date: 00/1990
Origin: ARI
ARI Keywords: Stellar Photospheres: M Giants, Stellar
Photospheres: UV Spectra, Stellar Photospheres:
Synthetic Spectra
Bibliographic Code: 1990ASPC....9...65W
Abstract
The authors present here some results of modeling the spectrum of the
M-giant star gamma Cru using similar techniques as those in their
study of Arcturus (Carpenter and Wahlgren, 1990 - see Abstr. 52.114.89).
Title: Modeling the ultraviolet photospheric spectrum of
cool giant stars. I - Arcturus. II - Gamma Crucis
Authors: Carpenter, Kenneth G.; Wahlgren, Glenn M.
Affiliation: AA(NASA, Goddard Space Flight Center, Greenbelt,
MD), AB(Computer Sciences Corp., El Segundo, CA)
Publication: IN: Cool stars, stellar systems, and the sun;
Proceedings of the 6th Cambridge Workshop, Seattle,
WA, Sept. 18-21, 1989 (A91-44876 19-90). San
Francisco, CA, Astronomical Society of the Pacific,
1990, p. 64-69.
Publication Date: 00/1990
Category: Astrophysics
Origin: STI
NASA/STI Keywords: COOL STARS, GIANT STARS, PHOTOSPHERE, STELLAR
SPECTRA, ULTRAVIOLET SPECTRA, ABSORPTION SPECTRA,
IUE, LINE SPECTRA
Bibliographic Code: 1990ASPC....9...64C
Abstract
The UV photospheric spectra of cool giants are modeled analytically to
facilitate the identification of UV spectral features and aid in the
measurement of actual chromospheric flux at different wavelengths.
Atomic line data derived experimentally and semiempirically are used
with LTE model atmospheres by means of the SYNTHE FORTRAN code to
generate the synthetic spectra. Surface flux spectra are determined and
fitted to the absorption features of observed IUE high resolution
spectra, and the modeled results are compared to the observed spectra of
the cool giants Arcturus and the cooler Gamma Crucis. It is shown that
the synthetic spectra can be produced for the stars, and chromospheric
emission lines are thought to account for significant discrepancies
between observed and calculated values. Two new fluorescence mechanisms
are identified by modeling the ultraviolet photospheric spectrum of
Gamma Crucis.
Title: Modeling the UV Photospheric Spectrum of K-M Giant
Stars
Authors: Carpenter, K.; Wahlgren, G.
Publication: Bulletin of the American Astronomical Society, Vol.
21, p.1112
Publication Date: 09/1989
Origin: ADS
Bibliographic Code: 1989BAAS...21Q1112C
Abstract
Not Available
Title: Discovery of a cool expanding shell at -1200
kilometers per second around V471 Tauri
Authors: Sion, Edward M.; Bruhweiler, Fred C.;
Mullan, Dermott; Carpenter, Ken
Affiliation: AA(Villanova, University, PA), AB(Catholic
University of America, Washington, DC), AC(Delaware,
University, Newark), AD(NASA, Goddard Space Flight
Center, Greenbelt, MD)
Publication: Astrophysical Journal, Part 2 - Letters (ISSN
0004-637X), vol. 341, June 1, 1989, p. L17-L20.
Publication Date: 06/1989
Category: Astrophysics
Origin: STI
NASA/STI Keywords: ECLIPSING BINARY STARS, GAS EXPANSION, STELLAR
ENVELOPES, ULTRAVIOLET SPECTRA, ABSORPTION SPECTRA,
IUE, K STARS, SPECTRAL LINE WIDTH, STELLAR WINDS,
WHITE DWARF STARS
DOI: 10.1086/185447
Bibliographic Code: 1989ApJ...341L..17S
Abstract
High-resolution IUE spectra of V471 Tauri reveal the presence of a
very-high-velocity cool expanding gas in the line of sight to the binary
system with an expansion velocity of -1200 km/s. The summed strength of
the coadded absorption is 125 mA + or - 25 mA, with FWHM = 30 km/s. It
is suggested that the observed absorption may be related to the narrow
coadded absorption at -590 km/s noted by Bruhweiler and Sion (1966). The
large expansion velocity suggests a possible association with an ancient
nova outburst.
Title: Evidence for a cool wind from the K2 dwarf in the
detached binary V471 Tauri
Authors: Mullan, D. J.; Sion, E. M.; Bruhweiler, F. C.;
Carpenter, K. G.
Affiliation: AA(Delaware, University, Newark), AB(Villanova
University, PA), AC(Catholic University of America,
Washington, DC), AD(NASA, Goddard Space Research
Center, Greenbelt, MD)
Publication: Astrophysical Journal, Part 2 - Letters (ISSN
0004-637X), vol. 339, April 1, 1989, p. L33-L36.
Publication Date: 04/1989
Category: Astrophysics
Origin: STI
NASA/STI Keywords: DWARF STARS, ECLIPSING BINARY STARS, STELLAR MASS
EJECTION, STELLAR WINDS, ABSORPTION SPECTRA,
CHROMIUM, IRON, MAGNESIUM, MANGANESE
DOI: 10.1086/185413
Bibliographic Code: 1989ApJ...339L..33M
Abstract
Evidence for mass loss from the K2 dwarf in V471 Tauri is found in the
form of discrete absorption features in lines of various elements (Mg,
Fe, Cr, Mn) and ionization stages (Mg I, Mg II, Fe I, Fe II). Resonant
Mg II absorption indicates a mass loss rate of at least 10 to the -11th
solar masses per year. The wind appears to be cool (no more than a few
times 10,000 K).
Title: Far-UV Low Resolution Spectroscopy of High
Luminosity K and M Stars
Authors: Carpenter, Kenneth G.
Publication: IUE Proposal ID \#LSLKC
Publication Date: 00/1989
Origin: IUE
Bibliographic Code: 1989iue..prop.3391C
Abstract
We propose the acquisition of SWP low resolution spectra of K - M bright
giants and supergiants to allow us to: 1) determine the underlying cause
of the extreme weakness of certain fluorescent features, e.g. O I (UV
2), in the spectrum of a minority of such stars, 2) extend our emission
measure analysis, and thus place improved constraints on the
distribution of the emitting chromospheric plasma with temperature and
density, to lower gravity, cooler effective temperatures, and 3)
estimate the mean relative intensities of the Lyman-alpha and Lyman Beta
lines within the stellar chromospheres. Used in conjunction with
archival data, these spectra will also allow us to determine: 4) the
dependence of radiative loss rates from cool star chromospheres on Teff
and luminosity, 5) whether there is a gradual shift in the relative
importance, to the chromospheric cooling, of higher and lower
temperature species as we go to cooler and more luminous stars, and 6)
whether there is a general trend of increasing flux in fluorescent
species with decreasing effective temperature and increasing luminosity.
In addition, these now spectra will be very valuable in optimizing the
choice of such objects to be observed at higher resolution and higher
signal/noise with the Hubble Space Telescope.
Title: Short Timescale Variations in the Outer Atmosphere
of Gamma Crucis
Authors: Carpenter, Kenneth G.
Publication: IUE Proposal ID \#LGLKC
Publication Date: 00/1989
Origin: IUE
Bibliographic Code: 1989iue..prop.3390C
Abstract
We propose the acquisition of a series of UV spectra of the M-giant
Gamma Cru to search for short timescale (i.e. 1 - 10 day) variations in
the chromosphere and UV spectrum of the star. Our primary probes will be
the numerous Fe II lines seen throughout the 2200 - 3200 A region, along
with the Mg II h and k lines and the C II (UV 0.01) intercombination
lines. High resolution line profiles and accurate fluxes will provide a
comprehensive probe of the state (density, temperature) and stability
(velocity field) of the outer atmosphere. The C II lines will be used to
monitor changes in the electron density, while the behavior of the Fe II
and Mg II lines can be used to study changes in the velocity of the wind
versus radius and time. The outward motion of any chromospheric event
will be followed by examining Fe II lines of differing optical depths,
and thus differing formation heights, in the time series. Any detected
variations will provide valuable clues toward understanding the
excitation mechanism(s) of individual Fe II lines, and especially aid
our attempts to distinguish lines dominated by photo-excitation
processes (e.g. Lyman-alpha/Fe II fluorescence) from those primarily
excited by collisions. This latter work will support the goals of 2
major ADP program submitted in the current proposal cycle.
Title: The winds of high luminosity late-type bright stars
Authors: Stencel, Robert E.; Carpenter, K. G.
Affiliation: AA(Colorado Univ., Boulder.)
Publication: Final Report, 15 Jun. 1986 - 14 Jun. 1989 National
Aeronautics and Space Administration. Goddard Space
Flight Center, Greenbelt, MD.
Publication Date: 00/1989
Category: Astrophysics
Origin: STI
NASA/STI Keywords: CHROMOSPHERE, K STARS, LATE STARS, M STARS, STELLAR
ENVELOPES, STELLAR LUMINOSITY, STELLAR WINDS, WIND
VELOCITY, ASYMMETRY, FINE STRUCTURE, FLUORESCENCE,
HIGH RESOLUTION, HUBBLE SPACE TELESCOPE, HYDROGEN,
SPECTROGRAPHS, VELOCITY DISTRIBUTION
Bibliographic Code: 1989gsfc.reptQ....S
Abstract
The occurrence and characteristics of the Fe II line asymmetries were
studied to determine the radial dependence of the wind velocity for each
star. The dependence of the Fe II profiles on spectral type and
luminosity class and thus the variation of the velocity fields with
stellar type was also investigated. This allows the generality of the
results reported for alpha Ori by Carpenter (1984b) to be judged. In
addition, new atomic data was used along with observations of the C II
(UV 0.01) multiplet to estimate Ne in the stellar winds.
Measures of relative Fe II fluxes can be used in a probability-of-escape
model to determine the opacity and hydrogen column density versus height
in the chromosphere of each star. Finally, analysis of the fluorescent
Fe II lines (pumped by Ly alpha) near 2507 A will yield estimates of the
intrinsic stellar Ly alpha flux that cannot be measured directly because
of interstellar and circumstellar absorption. One important goal of the
effort was to acquire high resolution spectra of the whole 2300 to 3200
A region of 13 luminous K and M stars as a data base that will be
enormously valuable in planning observations with the Hubble Space
Telescope High Resolution Spectrograph. It is also proposed to follow up
the recent discovery of significant variations in the Fe II
chromospheric emission line profiles from the M-giant Gamma Cru for the
purpose of determining the underlying cause of the variations.
Title: Fluorescence in the Outer Atmospheres of Red Giant
Stars
Authors: Carpenter, K. G.
Publication: Evolution of Peculiar Red Giant Stars, Proceedings
of IAU Colloq. 106, held in Bloomington, IN, 27-29
July 1988. Edited by H.R. Johnson and B. Zuckerman.
Cambridge Univ. Press, 1989., p.372
Publication Date: 00/1989
Origin: ADS
Bibliographic Code: 1989eprg.proc..372C
Abstract
Not Available
Title: V471 Tauri
Authors: Sion, E. M.; Bruhweiler, F. C.; Carpenter, K.;
Mullan, D. J.
Publication: IAU Circ., 4667, 2 (1988). Edited by Green, D. W.
E.
Publication Date: 10/1988
Origin: CBAT
Objects: V471 Tau
Bibliographic Code: 1988IAUC.4667....2S
Abstract
IAUC 4667 available at Central Bureau for Astronomical Telegrams.
IAUC 4667 available at Central Bureau for Astronomical Telegrams.
Title: The ultraviolet spectrum of noncoronal late-type
stars - The Gamma Crucis (M3.4 III) reference
spectrum
Authors: Carpenter, Kenneth G.; Pesce, Joseph E.;
Stencel, Robert E.; Brown, Alexander;
Johansson, Sveneric; Wing, Robert F.
Affiliation: AA(NASA, Goddard Space Flight Center, Greenbelt, MD;
Colorado, University, Boulder), AB(Colorado,
University, Boulder), AC(Colorado, University,
Boulder), AD(Joint Institute for Laboratory
Astrophysics, Boulder, CO), AE(NASA, Goddard Space
Flight Center, Greenbelt, MD)
Publication: Astrophysical Journal Supplement Series (ISSN
0067-0049), vol. 68, Oct. 1988, p. 345-369.
Publication Date: 10/1988
Category: Space Radiation
Origin: STI
NASA/STI Keywords: LATE STARS, M STARS, STELLAR ATMOSPHERES, STELLAR
CORONAS, SUPERGIANT STARS, ULTRAVIOLET SPECTRA,
EMISSION SPECTRA, HIGH RESOLUTION, HUBBLE SPACE
TELESCOPE, IUE
DOI: 10.1086/191291
Bibliographic Code: 1988ApJS...68..345C
Abstract
A guide is presented to the UV spectrum of M-type giants and supergiants
whose outer atmospheres contain warm chromospheres but not coronae. The
M3 giant Gamma Crucis is taken as the archetype of the cooler,
oxygen-rich, noncoronal stars. Line identifications and integrated line
flux measurements of the chromospheric emission features seen in the
1200-3200 A range of IUE high-resolution spectra are presented. The
major fluorescence processes operating in the outer atmosphere of Gamma
Crucis, including eight previously unknown pumping processes and 21 new
fluorescent line products, are summarized, and the enhancements of
selected line strengths by 'line leakage' is discussed. A set of
absorption features toward the longer wavelength end of this range is
identified which can be used to characterize the radial velocity of the
stellar photospheres. The applicability of the results to the spectra of
noncoronal stars with different effective temperatures and gravities is
discussed.
Title: V471 Tauri: The Oldest and Nearest Old Nova?
Authors: Sion, E. M.; Bruhweiler, F. C.; Carpenter, K.;
Mullan, D. J.
Publication: Bulletin of the American Astronomical Society, Vol.
20, p.1021
Publication Date: 09/1988
Origin: ADS
Bibliographic Code: 1988BAAS...20S1021S
Abstract
Not Available
Title: Detection of a Cool Wind From the K Dwarf in V471
Tauri
Authors: Mullan, D. J.; Sion, E. M.; Bruhweiler, F.;
Carpenter, K.
Publication: Bulletin of the American Astronomical Society, Vol.
20, p.997
Publication Date: 09/1988
Origin: ADS
Bibliographic Code: 1988BAAS...20..997M
Abstract
Not Available
Title: The Far-UV Spectrum of K and M Supergiant Stars
Authors: Carpenter, K. G.
Publication: Bulletin of the American Astronomical Society, Vol.
20, p.995
Publication Date: 09/1988
Origin: ADS
Bibliographic Code: 1988BAAS...20..995C
Abstract
Not Available
Title: What does C II lambda 2325 A emission tell us about
chromospheres of red supergiants? - A critical test
using Zeta Aurigae-type K supergiants
Authors: Schroeder, K.-P.; Reimers, D.; Carpenter, K. G.;
Brown, A.
Affiliation: AA(Hamburger Sternwarte, Hamburg, Federal Republic
of Germany), AB(Hamburger Sternwarte, Hamburg,
Federal Republic of Germany), AC(NASA, Goddard Space
Flight Center, Greenbelt, MD; Joint Institute for
Laboratory Astrophysics, Boulder, CO), AD(Joint
Institute for Laboratory Astrophysics, Boulder, CO)
Publication: Astronomy and Astrophysics (ISSN 0004-6361), vol.
202, no. 1-2, Aug. 1988, p. 136-142.
Publication Date: 08/1988
Category: Astrophysics
Origin: STI
NASA/STI Keywords: CARBON, CHROMOSPHERE, EMISSION SPECTRA, K STARS, RED
GIANT STARS, SUPERGIANT STARS, ELECTRON DENSITY
(CONCENTRATION), GAS IONIZATION, STELLAR MODELS
Bibliographic Code: 1988A&A...202..136S
Abstract
Line fluxes and intensity ratios of the C II UV 0.01 intercombination
multiplet near lambda2325 Å have been used by Carpenter et al.
(1985) to determine the density and the geometric extent of red giant
chromospheres. Here the authors test the limitations of the C II method
and the validity of the assumptions inherent in the method by means of
observations of C II 2325 Å emission of two stars (K type
supergiants zeta Aurigae, 32 Cygni) for which spatially resolved,
empirical model chromospheres has been derived earlier from high
resolution IUE observations at chromospheric eclipse phases
(Schröder, 1985).
Title: Calculation of mutual self inductance and coupling
coefficient for closely spaced loops
Authors: Carpenter, Kenneth H.
Affiliation: Kansas State Univ., Manhattan.
Publication: Final Report, 15 Apr. 1987 - 15 Apr. 1988 Kansas
State Univ., Manhattan. Dept. of Electrical and
Computer Engineering.
Publication Date: 06/1988
Category: Communications and Radar
Origin: STI
NASA/STI Keywords: COMPUTER AIDED DESIGN, COMPUTERIZED SIMULATION,
COUPLING COEFFICIENTS, INDUCTANCE, LOOPS, COMPUTER
PROGRAMS, ELECTRICAL RESISTIVITY, EQUIVALENT
CIRCUITS, FARADAY EFFECT, TRANSFORMERS
Bibliographic Code: 1988STIN...8919471C
Abstract
The magnetic coupling of closely spaced, flat loops has been studied,
assuming both coupling in air and coupling in the presence of ferrite
cores. The equivalent circuits for such coupled loops have been derived,
and the effect of resistance in the loops on measurements of coupling
evaluated. For loops typically used, conductor resistance was found to
have no significant effect on measurements. Series expansions for vector
potential and mutual inductance have been derived for circular flat
loops, and these expansions have been used to write a computer code,
COUPM2IN, which simulates the magnetic coupling accurately enough to be
used to aid air cored transformer design. With ferrite cores present the
magnetizing current is a much smaller fraction of transformer current
than with air cored design. Thus even though the models determined for
the ferrite cored inductors only approximately simulate the saturation
of the ferrite and the delay of the rotation of the magnetic domains,
these models can be used to aid ferrite cored transformer design. The
computer codes for both the air cored and ferrite cored cases are listed
in appendices. It is recommended that follow up work be undertaken to
refine the ferrite core modeling and to produce more robust computer
programs for transformer designers.
Title: Identification of new fluorescence processes in the
UV spectra of cool stars from new energy levels of
Fe II and CR II
Authors: Johansson, Sveneric; Carpenter, Kenneth G.
Affiliation: AA(Colorado Univ., Boulder.), AB(Colorado Univ.,
Boulder.)
Publication: In ESA, A Decade of UV Astronomy with the IUE
Satellite, Volume 1 p 361-363 (SEE N89-10682 01-89)
Publication Date: 06/1988
Category: Astronomy
Origin: STI
NASA/STI Keywords: COOL STARS, FLUORESCENCE, IUE, SPACEBORNE ASTRONOMY,
ULTRAVIOLET ASTRONOMY, ULTRAVIOLET SPECTRA,
CHROMIUM, EMISSION SPECTRA, IRON, LINE SPECTRA,
LYMAN ALPHA RADIATION, MOLECULAR ENERGY LEVELS
Bibliographic Code: 1988ESASP.281a.361J
Abstract
Two fluorescence processes operating in atmospheres of cool stars,
symbiotic stars, and the Sun are presented. Two emission lines, at
1347.03 and 1360.17 A, are identified as fluorescence lines of Cr II and
Fe II. The lines are due to transitions from highly excited levels,
which are populated radiatively by the hydrogen Lyman alpha line due to
accidental wavelength coincidences. Three energy levels, one in Cr II
and two in Fe II, are reported.
Title: Fluorescence processes and line identifications in
the UV spectra of cool stars
Authors: Carpenter, Kenneth G.; Johansson, Sveneric
Affiliation: AA(National Aeronautics and Space Administration.
Goddard Space Flight Center, Greenbelt, MD.),
AB(National Aeronautics and Space Administration.
Goddard Space Flight Center, Greenbelt, MD.)
Publication: In ESA, A Decade of UV Astronomy with the IUE
Satellite, Volume 1 p 349-356 (SEE N89-10682 01-89)
Publication Date: 06/1988
Category: Astronomy
Origin: STI
NASA/STI Keywords: CHROMOSPHERE, COOL STARS, FLUORESCENCE, IUE,
SPACEBORNE ASTRONOMY, ULTRAVIOLET ASTRONOMY,
ULTRAVIOLET SPECTRA, EMISSION SPECTRA, IRON, STELLAR
ATMOSPHERES
Bibliographic Code: 1988ESASP.281a.349C
Abstract
Fluorescence processes active in the outer atmospheres of noncoronal
cool stars and the UV lines they produce are summarized. Eight pumping
processes and 21 fluorescent line products are discussed. The processes,
which produce 12 lines, involves energy levels not previously known to
be radiatively populated. Four of these are examples of
self-fluorescence, whereby one or more lines of Fe II photo-excite
through coincident lines the upper levels of other Fe II lines lines
seen in emission, while two others explain the selective excitation of
solitary Ni II and Si I lines. Nine of the line products are decays from
levels in Fe I and Fe II already known to be radiatively populated.
Title: Direct UV observations of the circumstellar envelope
of alpha Orionis
Authors: Stencel, R. E.; Carpenter, K. G.; Pesce, J. E.;
Skinner, S.; Brown, A.; Judge, P.
Affiliation: AA(Joint Inst. for Lab. Astrophysics, Boulder,
Colo.), AB(Joint Inst. for Lab. Astrophysics,
Boulder, Colo.), AC(Joint Inst. for Lab.
Astrophysics, Boulder, Colo.), AD(Joint Inst. for
Lab. Astrophysics, Boulder, Colo.), AE(Joint Inst.
for Lab. Astrophysics, Boulder, Colo.), AF(Joint
Inst. for Lab. Astrophysics, Boulder, Colo.)
Publication: In ESA, A Decade of UV Astronomy with the IUE
Satellite, Volume 1 p 249-252 (SEE N89-10682 01-89)
Publication Date: 06/1988
Category: Astronomy
Origin: STI
NASA/STI Keywords: IUE, SPACEBORNE ASTRONOMY, STELLAR ENVELOPES,
SUPERGIANT STARS, ULTRAVIOLET ASTRONOMY, ULTRAVIOLET
SPECTRA, LIGHT SCATTERING, SIGNAL PROCESSING,
ULTRAVIOLET SPECTROSCOPY
Bibliographic Code: 1988ESASP.281a.249S
Abstract
Observations were made in the IUE LWP camera, low dispersion mode, with
alpha Ori being offset various distances from the center of the Long
Wavelength Large Aperture along its major axis. Signal was acquired at
all offset positions and is comprised of unequal components of
background/dark counts, telescope-scattered light, and scattered light
emanating from the extended circumstellar shell. The star is known from
optical and infrared observations to possess an extended, arc-minute
sized, shell of cool material. Attempts to observe this shell with the
IUE are described, although the deconvolution of the stellar signal from
the telescope scattered light requires further calibration effort.
Title: The Goddard High Resolution Spectrograph for the
Hubble Space Telescope: Pre-Launch Status
Authors: Brandt, J.; Ebbets, D.; Carpenter, K.; Heap, S.
Publication: Bulletin of the American Astronomical Society, Vol.
20, p.677
Publication Date: 03/1988
Origin: ADS
Bibliographic Code: 1988BAAS...20..677B
Abstract
Not Available
Title: Dinosaur Bone Beds and Mass Mortality: Implications
for the K-T Extinction
Authors: Carpenter, K.
Publication: Abstracts Presented to the Topical Conference on
Global Catastrophes in Earth History: An
Interdisciplinary Conference on Impacts, Volcanism,
and Mass Mortality. Held October 20-23, 1988, in
Snowbird, Utah. Sponsored by the Lunar and Planetary
Institute and the National Academy of Sciences. LPI
Contribution 673, published by the Lunar and
Planetary Institute, 3303 Nasa Road 1, Houston, TX
77058, 1988, p.24
Publication Date: 00/1988
Origin: ADS
Bibliographic Code: 1988LPICo.673...24C
Abstract
Not Available
Title: Far-UV Low Resolution Spectroscopy of M Supergiants
Authors: Carpenter, Kenneth G.
Publication: IUE Proposal ID \#LSKKC
Publication Date: 00/1988
Origin: IUE
Bibliographic Code: 1988iue..prop.3079C
Abstract
We propose the acquisition of SWP low resolution spectra of two M
supergiants. Our emission measure analysis which derive approximate
structure models of the outer atmospheric layers will be extended to
lower gravity, cooler effective temperatures with these data. In
combination with archive data, these spectra will be used to determine:
1) the dependence of radiative loss rates from cool star chromospheres
on Teff and luminosity, 2) whether there is a gradual shift in the
relative importance, to the chromospheric cooling, of higher and lower
temperature species as we go to cooler and more luminous stars, 3)
whether there is a general trend of increasing flux in fluorescent
species with decreasing effective temperature and increasing luminosity
and 4) whether the weakness of specific fluorescent lines in Alpha Ori
is a general characteristic of M supergiants or is unique to Alpha Ori.
In addition, these new spectra will be very valuable in optimizing the
choice of such objects to be observed at higher resolution and higher
signal/noise with the Hubble Space Telescope.
Title: Space telescope and the Fe II problem
Authors: Carpenter, Kenneth G.
Affiliation: AA(Colorado, University, Boulder)
Publication: IN: Physics of formation of FeII lines outside LTE;
Proceedings of the Ninety-fourth IAU Colloquium,
Anacapri, Italy, July 4-8, 1986 (A88-39176 15-90).
Dordrecht, D. Reidel Publishing Co., 1988, p.
323-328.
Publication Date: 00/1988
Category: Astronomy
Origin: STI
NASA/STI Keywords: ASTRONOMICAL SPECTROSCOPY, FAINT OBJECT CAMERA,
HUBBLE SPACE TELESCOPE, IRON, IUE, LINE SPECTRA,
SPATIAL RESOLUTION, SPECTRAL RESOLUTION
Bibliographic Code: 1988ASSL..138..323C
Abstract
The capabilities of the Hubble Space Telescope, especially as they apply
to the "Fe II problem" are reviewed. The major spectroscopic observing
modes of both the Faint Object Spectrograph and the High Resolution
Spectrograph are discussed and compared with those of the IUE satellite,
with a detailed illustrative look at the options available for
observations of Fe II (UV 1) near 2600 Å. Finally, the major
impacts to be expected on astrophysical investigations of Fe II from the
Space Telescope and associated instrumentation are summarized.
Title: Fe II emission line profiles in the ultraviolet
spectrum of cool, luminous stars
Authors: Carpenter, Kenneth G.
Affiliation: AA(Colorado, University, Boulder)
Publication: IN: Physics of formation of FeII lines outside LTE;
Proceedings of the Ninety-fourth IAU Colloquium,
Anacapri, Italy, July 4-8, 1986 (A88-39176 15-90).
Dordrecht, D. Reidel Publishing Co., 1988, p.
95-105.
Publication Date: 00/1988
Category: Astrophysics
Origin: STI
NASA/STI Keywords: COOL STARS, EMISSION SPECTRA, IRON, LINE SPECTRA,
STELLAR SPECTRA, ULTRAVIOLET SPECTRA, CHROMOSPHERE,
LATE STARS, STELLAR LUMINOSITY, STELLAR WINDS
Bibliographic Code: 1988ASSL..138...95C
Abstract
The differences between the outer atmospheres of the coronal and
noncoronal cool stars and the importance of massive stellar winds to the
latter group are summarized. The utility of Fe II as a probe of such
winds is indicated and a brief review of previous observations of Fe II
in these stars is given. The early results of a current IUE program to
study the chromospheres and winds of the noncoronal, late-type stars are
presented, including evidence of a strong dependence of the mid-UV Fe II
profiles on stellar luminosity. In addition, the dependence of the Fe II
profiles on intrinsic line strength in spectra of Alpha Ori and the
discovery of a variation of the Fe II profiles with time in spectra of
Gamma Cru are discussed.
Title: Emission Line Variations in the UV Spectrum of
Gacrux
Authors: Carpenter, K. G.
Publication: Bulletin of the American Astronomical Society, Vol.
19, p.1026
Publication Date: 09/1987
Origin: ADS
Bibliographic Code: 1987BAAS...19.1026C
Abstract
Not Available
Title: Observaciones con IUE e IRAS de gigantes y
supergigantes rojas.
Authors: Hagen, W.; Carpenter, K. G.; Stencel, R. E.
Publication: Rev. Mex. Astron. Astrofis., Vol. 14, No. 1, p. 380
Publication Date: 05/1987
Origin: ARI
ARI Keywords: Circumstellar Shells:Infrared Radiation,
Circumstellar Shells:Red Giants, Circumstellar
Shells:Red Supergiants, Infrared
Radiation:Circumstellar Shells, Red
Giants:Circumstellar Shells, Red
Supergiants:Circumstellar Shells
Bibliographic Code: 1987RMxAA..14..380H
Abstract
Abstract image available at:
http://esoads.eso.org/abs/1987RMxAA..14..380H
Title: The Goddard High Resolution Spectrograph for the
Hubble Space Telescope Status June 1987
Authors: Brandt, J.; Heap, S.; Carpenter, K.; Ebbets, D.;
Lindler, D.
Publication: Bulletin of the American Astronomical Society, Vol.
19, p.757
Publication Date: 03/1987
Origin: ADS
Bibliographic Code: 1987BAAS...19..757B
Abstract
Not Available
Title: A Roadmap to the Ultraviolet Spectrum of Cool,
Non-Coronal Stars
Authors: Carpenter, K. G.; Peace, J.; Stencel, R. E.;
Brown, A.
Publication: Bulletin of the American Astronomical Society, Vol.
19, p.705
Publication Date: 03/1987
Origin: ADS
Bibliographic Code: 1987BAAS...19..705C
Abstract
Not Available
Title: Mg II Emission Lines in the Spectra of Cool, High
Luminosity Stars
Authors: Carpenter, K. G.; Stencel, R. E.; Pesce, J. E.
Publication: Cool Stars, Stellar Systems and the Sun, Proceedings
of the Fifth Cambridge Workshop held in Boulder,
Colo., 8-11 Jul. 1987. Lecture Notes in Physics,
Vol. 291, edited by J. L. Linsky and R. E. Stencel.
Springer-Verlag, Berlin, 1987., p.164
Publication Date: 00/1987
Origin: ADS
DOI: 10.1007/3-540-18653-0_126
Bibliographic Code: 1987LNP...291..164C
Abstract
The authors present the initial results of a survey of the Mg II
emission lines in the spectra of K and M giants, bright giants, and
supergiants. Profiles of the Mg II h and k lines in 12 such stars are
shown in a relative spectral type/luminosity class grid. Plots based on
the h-line data illustrate the existence of a Wilson-Bappu effect in
these lines and of a slight dependence of the line asymmetry on V-R
color. A time series of Mg II profiles for the M3 giant Gamma Cru show
that the Mg II profiles have not undergone the profile shape changes
seen in the Fe II lines from this star over the same time period.
Title: 119 Tau
Authors: Carpenter, Kenneth
Publication: IUE Proposal ID \#OD28Y
Publication Date: 00/1987
Origin: IUE
Bibliographic Code: 1987iue..prop.2919C
Abstract
Not Available
Title: Variations in the Chromosphere and Stellar Wind of
Gamma Crucis
Authors: Carpenter, Kenneth G.
Publication: IUE Proposal ID \#MGJKC
Publication Date: 00/1987
Origin: IUE
Bibliographic Code: 1987iue..prop.2752C
Abstract
We propose to follow up the recent discovery of significant variations
in the Fe II chromospheric emission line profiles from the M-giant Gamma
Cru for the purpose of determining the underlying cause of the
variations. The star will be observed at five different times during the
year with SWP low resolution and LWPHI and LWPLO resolution to determine
whether the apparent increase in the opacity of the stellar wind and
chromosphere is: 1) due to additional mass being added to the outer
atmosphere through a one-time ejection of mass or an increase in the
mass loss rate, or 2) due to a temporary or permanent increase in the
chromospheric heating rate, or 3) is a periodic effect due, for example,
to rotation and the resulting variable visibility of inhomogeneities in
the chromosphere. This star is the first single, non-Mira M-giant for
which there is clear evidence from UV lines of substantial chromospheric
variation. It is important that we monitor the development of this event
and attempt to understand its origin, while the capabilities of IUE are
still available to us.
Title: Correcting observed stellar Lyman alpha profiles for
the effects of interstellar absorption and
geocoronal emission
Authors: Neff, J. E.; Linsky, J. L.; Landsman, W. B.;
Carpenter, K. G.
Affiliation: AA(Joint Inst. for Lab. Astrophysics, Boulder,
Colo.)
Publication: In ESA Proceedings of an International Symposium on
New Insights in Astrophysics. Eight Years of UV
Astronomy with IUE p 669-672 (SEE N87-19150 11-88)
Publication Date: 09/1986
Category: Astronomy
Origin: STI
NASA/STI Keywords: GEOCORONAL EMISSIONS, INTERSTELLAR EXTINCTION, IUE,
LYMAN ALPHA RADIATION, STELLAR SPECTRA, ULTRAVIOLET
SPECTRA, LATE STARS, SPECTRUM ANALYSIS, STELLAR
ATMOSPHERES
Bibliographic Code: 1986ESASP.263..669N
Abstract
Techniques to compensate for interstellar absorption and geocoronal
emission in IUE studies of late stars atmospheres were developed. Thus
it is possible to determine the Lyman alpha flux from nearby cool stars
using the low-resolution spectra in the IUE archives. The accuracy of
such a procedure depends fundamentally upon the assumptions regarding
the shape of the intrinsic profile and the density and velocity
structure of the local interstellar medium, not upon measurement
uncertainties of the low-resolution spectra. Geocoronal emission and
saturated spectra are fatal only to a one-dimensional spectral analysis.
When both the spatial and the spectral dimensions are considered, the
observed Lyman alpha flux can be recovered.
Title: Fe II emission line profiles in spectra of high
luminosity non-coronal stars
Authors: Carpenter, K. G.
Affiliation: AA(Colorado Univ., Boulder.)
Publication: In ESA Proceedings of an International Symposium on
New Insights in Astrophysics. Eight Years of UV
Astronomy with IUE p 99-102 (SEE N87-19150 11-88)
Publication Date: 09/1986
Category: Astronomy
Origin: STI
NASA/STI Keywords: CHROMOSPHERE, COOL STARS, IRON, IUE, LINE SPECTRA,
STELLAR LUMINOSITY, STELLAR SPECTRA, STELLAR MASS
EJECTION, STELLAR WINDS, ULTRAVIOLET SPECTRA
Bibliographic Code: 1986ESASP.263...99C
Abstract
The results of a program to study the winds of noncoronal late-type
giant and supergiant stars with IUE are presented. The primary data for
this study are profiles, fluxes, and velocities of the Fe II emission
lines which occur throughout the 2200 to 3230 A region of the IUE long
wavelength spectrographs. The apparent dependence of the Fe II profiles
on stellar luminosity (surface gravity) and intrinsic line strength is
discussed. The discovery of significant changes in the Fe II profiles in
spectra of Gamma Crucis (M3 III), during the period 1978 to 1985, that
suggest a substantial change in its outer atmosphere is noted.
Title: Mg II Emission Line Variability of Hybrid
Chromosphere Stars
Authors: Brown, A.; Linsky, J. L.; Drake, S. A.;
Carpenter, K. G.
Publication: Bulletin of the American Astronomical Society, Vol.
18, p.983
Publication Date: 09/1986
Origin: ADS
Bibliographic Code: 1986BAAS...18S.983B
Abstract
Not Available
Title: Thermal Vacuum Test Results for the Hubble Space
Telescope High Resolution Spectrograph: II.
Scientific Performance
Authors: Ebbets, D.; Garner, H.; Carpenter, K. G.;
Brandt, J. C.; Heap, S.; Lindler, D.
Publication: Bulletin of the American Astronomical Society, Vol.
18, p.940
Publication Date: 09/1986
Origin: ADS
Bibliographic Code: 1986BAAS...18..940E
Abstract
Not Available
Title: Thermal Vacuum Test Results for the Hubble Space
Telescope High Resolution Spectrograph: I. UV
Optical Throughput
Authors: Carpenter, K. G.; Ebbets, D.; Garner, H.; Heap, S.;
Lindler, D.; Brandt, J. C.
Publication: Bulletin of the American Astronomical Society, Vol.
18, p.940
Publication Date: 09/1986
Origin: ADS
Bibliographic Code: 1986BAAS...18..940C
Abstract
Not Available
Title: Current Status of the High Resolution Spectrograph
(HRS) for the Hubble Space Telescope
Authors: Brandt, J. C.; Carpenter, K. G.; Ebbets, D.;
Garner, H.; Heap, S.; Lindler, D.
Publication: Bulletin of the American Astronomical Society, Vol.
18, p.940
Publication Date: 09/1986
Origin: ADS
Bibliographic Code: 1986BAAS...18..940B
Abstract
Not Available
Title: Ultraviolet and infrared observations of stars with
'quenched' chromospheres and the nature of mass loss
Authors: Stencel, R. E.; Carpenter, K. G.; Hagen, W.
Affiliation: AA(NASA, Astrophysics Div., Washington, DC),
AB(Joint Institute for Laboratory Astrophysics,
Boulder, CO), AC(Whitin Observatory, Wellesley, MA)
Publication: Astrophysical Journal, Part 1 (ISSN 0004-637X), vol.
308, Sept. 15, 1986, p. 859-867.
Publication Date: 09/1986
Category: Astrophysics
Origin: STI
NASA/STI Keywords: CHROMOSPHERE, INFRARED SPECTRA, INTERSTELLAR MATTER,
RED GIANT STARS, STELLAR MASS EJECTION, ULTRAVIOLET
SPECTRA, INTERSTELLAR GAS, INTERSTELLAR MASERS,
STELLAR ENVELOPES
DOI: 10.1086/164557
Bibliographic Code: 1986ApJ...308..859S
Abstract
Previous observational evidence implies that the presence of Ca II
emission, a chromospheric indicator, is correlated with the gas/dust
ratio in the envelopes of red giant and supergiant stars. An attempt is
made to determine whether this correlation can be generalized to all
chromospheric activity indicators and the gas/dust ratio. New
ultraviolet observations address the strength of UV emission features
and the fraction of the total chromospheric flux emitted in various
lines. Evidence is found that chromospheres are not completely quenched
in the presence of dust, but that significant alteration of relative
radiative loss patterns may occur. These observations are interpreted in
terms of an instability that converts warm, chromospheric gas into
near-surface dust grains and cool gas capable of supporting molecular
masing. This supports the dust-driven mass loss scenario for red giant
winds.
Title: IUE and IRAS observations of luminous M stars with
varying gas-to-dust ratios.
Authors: Hagen, W.; Carpenter, K. G.; Stencel, R. E.
Publication: NASA Conf. Publ., NASA CP-2403, p. A 8
Publication Date: 01/1986
Origin: ARI
ARI Keywords: Circumstellar Shells:Gas-to-Dust Ratios, Gas-to-Dust
Ratios:Circumstellar Shells
Bibliographic Code: 1986NASCP2403A...8H
Abstract
Not Available
Title: IUE and IRAS observations of luminous M stars with
varying gas-to dust ratios
Authors: Hagen, W.; Carpenter, K. G.; Stencel, R. E.
Affiliation: AA(New Mexico Univ., Albuquerque), AB(JILA)
Publication: In its Interrelationships among Circumstellar,
Interstellar and Interplanetary Dust 1 p (SEE
N86-23493 13-88)
Publication Date: 01/1986
Category: Astrophysics
Origin: STI
NASA/STI Keywords: DUST, GAS ANALYSIS, INFRARED ASTRONOMY SATELLITE,
IUE, M STARS, BALMER SERIES, CALCIUM, EMISSION
SPECTRA, LINE SPECTRA, MAGNESIUM
Bibliographic Code: 1986icii.reptQ....H
Abstract
Circumstellar gas and dust surrounding M giants and supergiants show
luminous M stars to split into two distinct classes. Stars with a high
gas to dust ratio all show chromospheric Ca II, H, and K emission. Stars
with a high dust to gas ratio do not show chromospheric Ca II emission
but are the only ones to show Balmer emission indicative of atmospheric
shocks and are also the only ones to show maser emission. In order to
determine whether all chromospheric indicators disappear in high dust to
gas ratio stars, a survey of stars in both these classes was conducted
with the IUE satellite. Long wavelength infrared fluxes for the program
stars were obtained from the IRAS point source catalog. There is no
obvious difference in the long wavelength observations between the two
groups of stars. The long wavelength excess tends to follow the 10
micron excess and not the dust to gas ratio.
Title: Efficiency functions for a 316 g/mm echelle grating
Authors: Cushman, G. W.; Carpenter, K. G.
Affiliation: AA(Ball Corp., Ball Aerospace Systems Div., Boulder,
CO), AB(Joint Institute for Laboratory Astrophysics,
Boulder, CO)
Publication: IN: Instrumentation in astronomy VI; Proceedings of
the Meeting, Tucson, AZ, Mar. 4-8, 1986. Part 1
(A87-36376 15-35). Bellingham, WA, Society of
Photo-Optical Instrumentation Engineers, 1986, p.
395-400.
Publication Date: 00/1986
Category: Optics
Origin: STI
NASA/STI Keywords: ECHELLE GRATINGS, RADIOMETRIC RESOLUTION,
TRANSMISSION EFFICIENCY, ANGULAR RESOLUTION,
CALIBRATING, HIGH RESOLUTION, HUBBLE SPACE
TELESCOPE, INCIDENCE, SPECTROGRAPHS
Bibliographic Code: 1986SPIE..627..395C
Abstract
The radiometric response function of the High Resolution Spectrograph
(HRS) for the Hubble Space Telescope was measured in 1984. From the
system efficiency measurements made in the HRS echelle modes, the
relative efficiencies ('ripple' functions) of 14 HRS echelle orders have
been deduced. The results agree well with a theoretical model of echelle
efficiency, except for a residual shift of apparent blaze angle with
spectral order. The discrepancy between nominal and fitted blaze angle
decreases with increasing order number.
Title: Optical, UV and Radio Observations of RS Canum
Venaticorum
Authors: Catalano, S.; Rodono, M.; Linsky, J. L.;
Carpenter, K.; Gibson, D.; Gary, D.; Butler, J.
Publication: Cool Stars, Stellar Systems and the Sun, Proceedings
of the Fourth Cambridge Workshop on Cool Stars,
Stellar Systems, and the Sun, Held in Santa Fe, New
Mexico, October 16-18, 1985. Lecture Notes in
Physics, Vol. 254, edited by Michael Zeilik and
David M. Gibson, Springer-Verlag, Berlin Heidelberg
New York, 1986., p.253
Publication Date: 00/1986
Origin: ADS
Bibliographic Code: 1986LNP...254..253C
Abstract
Preliminary results are reported on optical, UV and radio observations
of the binary system RS Canum Venaticorum carried out in March 1984, as
a part of the international coordinated programme on solar-like activity
in late type stars.
Title: An IUE High-Dispersion Cool-Star Atlas
Authors: Ayres, T. R.; Brugel, E. W.; Linsky, J. L.;
Brown, A.; Carpenter, K. G.
Publication: Cool Stars, Stellar Systems and the Sun, Proceedings
of the Fourth Cambridge Workshop on Cool Stars,
Stellar Systems, and the Sun, Held in Santa Fe, New
Mexico, October 16-18, 1985. Lecture Notes in
Physics, Vol. 254, edited by Michael Zeilik and
David M. Gibson, Springer-Verlag, Berlin Heidelberg
New York, 1986., p.106
Publication Date: 00/1986
Origin: ADS
Bibliographic Code: 1986LNP...254..106A
Abstract
The authors are planning to compile a spectral atlas based on
high-dispersion images of representative late-type stars recorded by the
International Ultraviolet Explorer. They solicit advice from the
ultraviolet community concerning how best to present the spectral
material.
Title: Gamma Crucis
Authors: Carpenter, Kenneth
Publication: IUE Proposal ID \#OD90K
Publication Date: 00/1986
Origin: IUE
Bibliographic Code: 1986iue..prop.2633C
Abstract
Not Available
Title: The Winds of High Luminosity K and M Stars
Authors: Carpenter, Kenneth G.
Publication: IUE Proposal ID \#MGIKC
Publication Date: 00/1986
Origin: IUE
Bibliographic Code: 1986iue..prop.2426C
Abstract
The winds of high luminosity K and M stars likely play a major role in
stellar evolution, yet this region of the H-R diagram is one of the
least-studied with IUE, due to the very limited number of targets that
are bright in the ultraviolet. However, high-resolution spectra of the
long wavelength region of the few well-observed stars reveal extremely
interesting spectra containing dozens of broad, frequently self-reversed
and asymmetric Fe II emission lines in addition to the Mg II, Al II, and
C II lines seen in all late-type stars. We propose a comprehensive study
of a sample of 13 such stars using both archive and new observations. We
shall study the occurrence and characteristics of the Fe II line
asymmetries to determine the radial dependence of the wind velocity for
each star. We shall also investigate the dependence of the Fe II
profiles on spectral type and luminosity class and thus the variation of
the velocity fields with stellar type. This will allow us to judge the
generality of the results reported for alpha Ori by Carpenter (1984b).
In addition, we shall use new atomic data along with observations of the
C II(UV 0.01) multiplet to estimate Ne in the stellar winds. Measures of
relative Fe II fluxes will be used in a probability-of-escape model to
determine the opacity and hydrogen column density versus height in the
chromosphere of each star. Finally, analysis of the fluorescent Fe II
lines (pumped by Ly-alpha) near 2507 will yield estimates of the
intrinsic stellar Ly-alpha flux that cannot be measured directly because
of interstellar and circumstellar absorption. One important goal of this
proposal is to acquire high resolution spectra of the whole 2300-3200 A
region of 13 luminous K and M stars as a data base that will be
enormously valuable in planning observations with the Space Telescope
High Resolution Spectrograph, which will be able to observe only small
portions of the spectrum at one time with high sensitivity.
Title: Hydrogen Lyman Alpha Fluxes for Late-Type Dwarf
Stars
Authors: Neff, J. E.; Carpenter, K. G.; Ayres, T. R.
Publication: Bulletin of the American Astronomical Society, Vol.
17, p.879
Publication Date: 09/1985
Origin: ADS
Bibliographic Code: 1985BAAS...17..879N
Abstract
Not Available
Title: The Effect of Dust on the Chromospheres of Cool,
Luminous Stars
Authors: Carpenter, K. G.; Stencel, R. E.; Hagen, W.
Publication: Bulletin of the American Astronomical Society, Vol.
17, p.876
Publication Date: 09/1985
Origin: ADS
Bibliographic Code: 1985BAAS...17..876C
Abstract
Not Available
Title: Densities, Temperatures and Geometric Extents of C
II Emitting Regions in the Winds of Luminous,
Late-Type Stars
Authors: Carpenter, K. G.; Brown, A.; Stencel, R. E.
Publication: Mass Loss from Red Giants; Proceedings of the
Conference, University of California, Los Angeles,
CA, June 20, 21, 1984. Edited by M. Morris and B.
Zuckerman. Dordrecht, D. Reidel Publishing Co.
Astrophysics and Space Science Library. Volume 117,
1985, p.55
Publication Date: 07/1985
Origin: ADS
Bibliographic Code: 1985mlrg.proc...55C
Abstract
The authors summarize techniques for using IUE observations of the C II
UV 0.01 and UV 1 emission line multiplets at 2325 Å and 1335
Å to estimate the electron density (Ne) and temperature
(Te) in, and the geometric extent of, the chromospheres of
late-type stars. The results of applying these techniques to a sample of
15 stars observed with the IUE satellite are discussed.
Title: Laboratory Calibration of the High Resolution
Spectrograph for Space Telescope: Absolute
Sensitivity
Authors: Carpenter, K. G.; Cushman, G.; Ebbets, D.; Heap, S.;
Brandt, J.
Publication: Bulletin of the American Astronomical Society, Vol.
17, p.574
Publication Date: 03/1985
Origin: ADS
Bibliographic Code: 1985BAAS...17..574C
Abstract
Not Available
Title: Emission Line Variability of RY Tau, DR Tau and SU
Aur
Authors: Brown, A.; Walter, F. M.; Carpenter, K. G.;
Jordan, C.; Judge, P.
Publication: Bulletin of the American Astronomical Society, Vol.
17, p.556
Publication Date: 03/1985
Origin: ADS
Bibliographic Code: 1985BAAS...17..556B
Abstract
Not Available
Title: Line identifications, line strengths, and continuum
flux measurements in the ultraviolet spectrum of
Arcturus
Authors: Carpenter, K. G.; Wing, R. F.; Stencel, R. E.
Affiliation: AA(Ohio State University, Columbus, OH), AB(Ohio
State University, Columbus, OH), AC(Joint Institute
for Laboratory Astrophysics, Boulder, CO)
Publication: Astrophysical Journal Supplement Series (ISSN
0067-0049), vol. 57, Feb. 1985, p. 405-422.
Publication Date: 02/1985
Category: Astrophysics
Origin: STI
NASA/STI Keywords: GIANT STARS, LINE SPECTRA, STELLAR
SPECTROPHOTOMETRY, ULTRAVIOLET ASTRONOMY, FLUX
QUANTIZATION, IRON, IUE, SPACEBORNE ASTRONOMY,
SPECTRAL LINE WIDTH, TABLES (DATA)
DOI: 10.1086/191009
Bibliographic Code: 1985ApJS...57..405C
Abstract
The ultraviolet spectrum of Arcturus has been observed at high
resolution with the IUE satellite. Line identifications, mean absolute
'continuum' flux measurements, integrated absolute emission-line fluxes,
and measurements of selected absorption line strengths are presented for
the 2250-2930 A region. In the 1150-2000 A region, identifications are
given primarily on the basis of low-resolution spectra. Chromospheric
emission lines have been identified with low-excitation species
including H I, C I, C II, O I, Mg I, Mg II, Al II, Si I, Si II, S I, and
Fe II; there is no evidence for lines of C IV, N V, or other species
requiring high temperatures. A search for molecular absorption features
in the 2500-2930 A interval has led to several tentative
identifications, but only OH could be established as definitely present.
Iron lines strongly dominate the identifications in the 2250-2930 A
region, Fe II accounting for about 86 percent of the emission features
and Fe I for 43 percent of the identified absorption features.
Title: The geometric extent of C II (UV 0.01) emitting
regions around luminous, late-type stars
Authors: Carpenter, K. G.; Brown, A.; Stencel, R. E.
Affiliation: AA(Joint Institute for Laboratory Astrophysics,
Boulder, CO), AB(Joint Institute for Laboratory
Astrophysics, Boulder, CO), AC(NASA, Astrophysics
Div., Washington, DC; Joint Institute for Laboratory
Astrophysics, Boulder, CO)
Publication: Astrophysical Journal, Part 1 (ISSN 0004-637X), vol.
289, Feb. 15, 1985, p. 676-680.
Publication Date: 02/1985
Category: Astrophysics
Origin: STI
NASA/STI Keywords: CARBON STARS, CHROMOSPHERE, GIANT STARS, LATE STARS,
STELLAR ENVELOPES, ULTRAVIOLET SPECTRA, ELECTRON
DENSITY (CONCENTRATION), EMISSION SPECTRA, STELLAR
LUMINOSITY, STELLAR STRUCTURE, STELLAR TEMPERATURE,
SUPERGIANT STARS
DOI: 10.1086/162931
Bibliographic Code: 1985ApJ...289..676C
Abstract
A method is presented by which the geometric extent of the chromospheres
around late-type stars can be estimated from measurements of the total
emission-line flux and line ratios within the C II (UV 0.01) multiplet.
Application of this technique to a sample of 15 late-type stars
indicates a clear difference in the radial extent of the chromospheres
around coronal and noncoronal stars. The former stars appear to have
very thin chromospheres (of no more than 0.1 percent of the photospheric
radius), while the latter stars have chromospheres extending, on
average, out to 2.5 photospheric radii. This, in principle, provides
information for understanding structural differences between late-type
giant and supergiant stars with and without coronae, and could lead to
an understanding of the mass-loss mechanisms involved.
Title: The structures and spectra of magnetic,
line-blanketed model atmospheres
Authors: Carpenter, K. G.
Affiliation: AA(Joint Institute for Laboratory Astrophysics,
Boulder, CO; Ohio State University, Columbus, OH)
Publication: Astrophysical Journal, Part 1 (ISSN 0004-637X), vol.
289, Feb. 15, 1985, p. 660-668.
Publication Date: 02/1985
Category: Astrophysics
Origin: STI
NASA/STI Keywords: LINE SPECTRA, MAGNETIC STARS, PECULIAR STARS,
SPECTRAL ENERGY DISTRIBUTION, STELLAR ATMOSPHERES,
STELLAR MODELS, A STARS, ABUNDANCE, ATMOSPHERIC
PRESSURE, MAGNETIC FIELD CONFIGURATIONS, MAIN
SEQUENCE STARS, RADIANT FLUX DENSITY, STELLAR
TEMPERATURE, ZEEMAN EFFECT
DOI: 10.1086/162929
Bibliographic Code: 1985ApJ...289..660C
Abstract
Magnetic, line-blanketed model atmospheres for upper-main-sequence stars
with normal elemental abundances and a slightly distorted dipolar
magnetic field have been constructed. These were computed with a
modified version of the Kurucz ATLAS6 model atmosphere code and newly
computed opacity distribution functions (ODFs), which take into account
the Zeeman splitting of the contributing atomic lines. The inclusion of
magnetic forces changes the structure of an atmosphere by altering the
net gravity and thus the pressure distribution in the upper layers of
the atmosphere. These magnetic forces cause the structure of the stellar
model to vary with latitude and to differ from the nonmagnetic case. The
enhanced blanketing represented by the 'magnetic' ODFS in combination
with the structure changes and Zeeman broadening of individual lines
causes the emergent spectrum to vary with viewing inclination and to
differ from the nonmagnetic case. The structure and spectrum
computations are described and results compared with those for
nonmagnetic models. The results are discussed in light of existing
observations of Ap stars, which are thought to have magnetic field
configurations similar to the ones included in these models.
Title: Chromospheric emission lines in high-resolution LWR
spectra (220 - 3000 alpha) of gamma CRU (M3 3) and
alpha ORI (M2 Iab)
Authors: Carpenter, K. G.
Affiliation: AA(Joint Inst. for Lab. Astrophysics, Boulder, CO.)
Publication: In NASA. Goddard Space Flight Center Future of
Ultraviolet Astronomy Based on Six Years of IUE Res.
p 450-453 (SEE N85-20961 11-89)
Publication Date: 12/1984
Category: Astronomy
Origin: STI
NASA/STI Keywords: CHROMOSPHERE, EMISSION SPECTRA, LINE SPECTRA, STARS,
STELLAR WINDS, ULTRAVIOLET SPECTRA, ELECTRON DENSITY
(CONCENTRATION), IUE, ULTRAVIOLET ASTRONOMY
Bibliographic Code: 1984NASCP2349..450C
Abstract
The identity and characteristics of the chromospheric emission features
in the 2200 to 300 A region of high resolution spectra of the stars
gamma Cru and alpha Ori are summarized. The velocities, fluxes, and
asymmetries of a set of Fe II lines which share common upper or lower
energy levels are discussed and the information gained from flux
measurements of the C II (UV 0.01) lines is presented. The Fe II lines
in the alpha Ori spectra indicate the general shape of the velocity
versus radius relation in its wind. The C II (UV 0.01) data are combined
with measures of the C II (UV 1) flux to estimate the electron density
and temperature in the wind and the geometric extent of the C II
emitting region in both stars.
Title: A progress report on the analysis of long exposure
SWP high resolution spectra of cool stars
Authors: Linsky, J. L.; Ayres, T. R.; Brown, A.;
Carpenter, K. G.; Jordon, C.; Judge, P.;
Gustafsson, B.; Eriksson, E.; Saxner, M.;
Engvold, O.
Affiliation: AA(Colorado Univ., Boulder), AB(Colorado Univ.,
Boulder), AC(Oxford Univ., England), AD(Oxford
Univ., England), AE(Oxford Univ., England),
AF(Oxford Univ., England), AG(Uppsala Univ.,
Sweden), AH(Uppsala Univ., Sweden), AI(Uppsala
Univ., Sweden), AJ(Oslo Univ., Norway)
Publication: In NASA. Goddard Space Flight Center Future of
Ultraviolet Astronomy Based on Six Years of IUE Res.
p 445-449 (SEE N85-20961 11-89)
Publication Date: 12/1984
Category: Astronomy
Origin: STI
NASA/STI Keywords: HIGH RESOLUTION, IUE, LATE STARS, STELLAR
ATMOSPHERES, ULTRAVIOLET SPECTRA, ATMOSPHERIC
MODELS, BINARY STARS, DATA REDUCTION, DWARF STARS,
GIANT STARS, SUPERGIANT STARS, TABLES (DATA)
Bibliographic Code: 1984NASCP2349..445L
Abstract
The IUE is the first experiment with sufficient sensitivity to obtain
high resolution spectra (lambda/delta lambda is approximately 10,000) of
many cool stars in the vitally important 1200 to 2000 A spectral region.
These data provide qualitatively new information with which to
understand the properties of and structures in the outer atmospheres of
these stars. Also, these cool star spectra will be extremely useful in
planning for the Space Telescope High Resolution Spectrograph, which
will be 1000 times more sensitive than IUE but will be hampered by
limited observing time and limited spectral bandwidth in each exposure.
Very long exposure, high disperson SWP spectra of many stars located
throughout the cool half of the HR diagram were obtained. These 12 to 21
hour exposures were obtained by combining NASA and Vilspa shifts so as
to obtain the longest possible exposures at times of low background.
Included are dwarf stars of spectral type G0 V to M2 V, G9.5 III to M5
II giants, G2 Ib to M2 Iab supergiants, a number of RS CVn-type systems,
and Barium stars.
Title: The temperature of C II emission-line formation
regions in cool stars
Authors: Brown, A.; Carpenter, K. G.
Affiliation: AA(Joint Institute for Laboratory Astrophysics,
Boulder, CO), AB(Joint Institute for Laboratory
Astrophysics, Boulder, CO)
Publication: Astrophysical Journal, Part 2 - Letters to the
Editor (ISSN 0004-637X), vol. 287, Dec. 1, 1984, p.
L43-L46.
Publication Date: 12/1984
Category: Astrophysics
Origin: STI
NASA/STI Keywords: CARBON STARS, COOL STARS, GIANT STARS, LATE STARS,
STELLAR SPECTRA, STELLAR TEMPERATURE, SUPERGIANT
STARS, EMISSION SPECTRA, IUE, LINE SPECTRA
DOI: 10.1086/184394
Bibliographic Code: 1984ApJ...287L..43B
Abstract
An investigation has been conducted of the temperature of C II
emission-line formation regions in the outer atmospheres of late-type
giant and supergiant stars. A distinct dichotomy is seen in the C II
lambda 2325/lambda 1335 ratio between coronal and noncoronal stars. It
is found that C II emission from noncoronal giant and supergiant stars
comes from regions with temperatures of 7000-9000 K, with the mean
temperature being approximately 8500 K, whereas the C II emission from
coronal stars likely comes from hotter regions. The C II ratio provides
a powerful empirical tool for estimating the chromospheric temperatures
of cool giants and supergiants.
Title: On the nonexistence of "Ampere tension" in electric
conductors
Authors: Carpenter, K.; Graneau, P.
Publication: IEEE Transactions on Magnetics, vol. 20, issue 6,
pp. 2159-2160
Publication Date: 11/1984
Origin: CROSSREF
DOI: 10.1109/TMAG.1984.1063571
Bibliographic Code: 1984ITM....20.2159C
Abstract
Not Available
Title: Rotational velocities of later B type and A type
stars as determined from ultraviolet versus visual
line profiles
Authors: Carpenter, K. G.; Slettebak, A.; Sonneborn, G.
Affiliation: AA(Perkins Observatory, Delaware, OH), AB(Perkins
Observatory, Delaware, OH), AC(Perkins Observatory,
Delaware, OH)
Publication: Astrophysical Journal, Part 1 (ISSN 0004-637X), vol.
286, Nov. 15, 1984, p. 741-746.
Publication Date: 11/1984
Category: Astrophysics
Origin: STI
NASA/STI Keywords: A STARS, ANGULAR VELOCITY, B STARS, STELLAR
ROTATION, ULTRAVIOLET SPECTRA, VISIBLE SPECTRUM,
EARLY STARS, IRON, IUE, LINE SHAPE, SILICON,
SPECTRUM ANALYSIS, STELLAR MODELS
DOI: 10.1086/162650
Bibliographic Code: 1984ApJ...286..741C
Abstract
Theoretical line profiles of the Si III 1299 and Fe II 2756 lines are
computed for rotating B5-A7 model stars, and compared with observed
profiles from IUE spectra to derive rotational velocities. Real
differences in widths for ultraviolet as compared with visual line
profiles exist in the sample of B type stars (but not for the A type
rapidly rotating stars), although these are not as large as previously
reported in the literature. Comparison with the theoretical line
profiles gives rotational velocities that are in good agreement with
visually determined v sin i values for the same stars, which suggests
that the shape-distorted, gravity-darkened models are reasonable.
Title: Research support for plasma diagnostics on Elmo
Bumpy Torus: Diamagnetic measurements and data
analysis and development of ring models for
realistic representation of fields near the plasma
Authors: Carpenter, K. H.; Steimle, R. F.
Affiliation: Missouri Univ., Rolla.
Publication: Final Report, 1 Oct. 1983 - 30 Sep. 1984 Missouri
Univ., Rolla. Dept. of Electrical Engineering.
Publication Date: 10/1984
Category: Plasma Physics
Origin: STI
NASA/STI Keywords: BUMPY TORUSES, PLASMA DIAGNOSTICS, ELECTRONS, FUSION
REACTORS, HALL EFFECT, MAGNETIC PROBES
Bibliographic Code: 1984umo..rept.....C
Abstract
Theoretical and experimental studies relating to the diamagnetism of the
Elmo Bumpy Torus (EBT) electron rings contributed to a better
understanding of ring and geometry. The primary experimental effort
during the past year was the taking of data using the UMR Hall effect
diamagnetic diagnostic instrument with the probes mounted along the
horizontal midplane at the large major radius position of an EBT cavity.
Analysis of this data confirmed earlier indications of an electron ring
component being present near the cavity wall.
Title: Characteristics of the Fe II and C II emission in
high-resolution IUE spectra (2300-3000 A) of Alpha
Orionis
Authors: Carpenter, K. G.
Affiliation: AA(Joint Institute for Laboratory Astrophysics,
Boulder, CO)
Publication: Astrophysical Journal, Part 1 (ISSN 0004-637X), vol.
285, Oct. 1, 1984, p. 181-189.
Publication Date: 10/1984
Category: Astrophysics
Origin: STI
NASA/STI Keywords: EMISSION SPECTRA, LINE SHAPE, SATELLITE OBSERVATION,
STELLAR SPECTRA, SUPERGIANT STARS, ULTRAVIOLET
SPECTRA, CARBON, CHROMOSPHERE, HIGH RESOLUTION,
IRON, IUE, STELLAR ATMOSPHERES
DOI: 10.1086/162489
Bibliographic Code: 1984ApJ...285..181C
Abstract
A study is presented of Fe II and C II emission features in the
2300-3000 A region of four high-resolution IUE spectra of Alpha Ori
obtained during the period 1978 April-1982 November. A set of 42
unmutilated, unblended Fe II lines of multiplets UV 1-3, 32-33, 35-36,
and 60-64 and the C II (UV 0.01) intercombination lines have been
identified and measured to determine their velocities, fluxes, and
asymmetries. A correlation of Fe II line asymmetry with intrinsic line
strength indicates a velocity field which is initially constant, then
algebraically increases with radius to a maximum value and then
decreases significantly before reaching an asymptotic flow speed far
from the star. The mean velocity of the chromospheric regions emitting
Fe II does not appear to differ substantially from the time-average of
the photospheric velocity, but there is evidence that the two regions
are not strongly coupled and thus that the chromosphere does not
strictly follow the semiperiodic 6 year pulsations of the photosphere.
An analysis of the C II line fluxes produces estimates of the electron
density in the chromosphere in the range 3.2 x 10 to the 7th-1.3 x 10 to
the 8th per sq cm and indicates that the region emitting C II is
geometrically thick, extending at least one-tenth, and perhaps as far as
1.2, photospheric radii from the base of the chromosphere.
Title: Atmospheric Structures in AR Lac. I. Mapping
Quiescent Features by Occultations &Doppler Imaging
Authors: Walter, F. M.; Gibson, D. M.; Brown, A.;
Carpenter, K.; Linsky, J. L.; Rodono, M.; Eyles, C.
Publication: Bulletin of the American Astronomical Society, Vol.
16, p.896
Publication Date: 09/1984
Origin: ADS
Bibliographic Code: 1984BAAS...16R.896W
Abstract
Not Available
Title: IUE and IRAS Observations of Luminous M Stars with
Varying Gas-to-Dust Ratios
Authors: Hagen, W.; Carpenter, K. G.; Stencel, R. E.
Publication: Bulletin of the American Astronomical Society, Vol.
16, p.895
Publication Date: 09/1984
Origin: ADS
Bibliographic Code: 1984BAAS...16..895H
Abstract
Not Available
Title: FRONTIERS - Progress with a System for Nowcasting
Rain
Authors: Carpenter, K. M.; Browning, K. A.
Publication: Nowcasting II, Mesoscale Observations and
Very-Short-Range Weather Forecasting, Proceedings of
the Second International Symposium held 3-7
September, 1984 in Norrköping, Sweden. ESA SP-208.
Paris: European Space Agency, 1984., p.427
Publication Date: 06/1984
Origin: ADS
Bibliographic Code: 1984ESASP.208..427C
Abstract
Not Available
Title: Book-Review - Atlas of High Resolution IUE Spectra
of Late-Type Stars 2500-3230A
Authors: Wing, R. F.; Carpenter, K. G.; Wahlgren, G. M.
Publication: SKY AND TELESCOPE V.67:6, P.527, 1984
Publication Date: 00/1984
Origin: KNUDSEN
Bibliographic Code: 1984S&T....67R.527W
Abstract
Not Available
Title: Evidence suggesting gradual extinction of latest
cretaceous Dinosaurs
Authors: Carpenter, K.
Affiliation: AA(University of Colorado Museum)
Publication: Naturwissenschaften, Volume 70, Issue 12, pp.611-612
Publication Date: 12/1983
Origin: SPRINGER
Abstract Copyright: (c) 1983: Springer-Verlag
DOI: 10.1007/BF00377404
Bibliographic Code: 1983NW.....70..611C
Abstract
Not Available
Title: Ultraviolet spectroscopic observations of some Be
stars of later type and A-F type shell stars
Authors: Slettebak, A.; Carpenter, K. G.
Affiliation: AA(Perkins Observatory, Delaware, OH)
Publication: Astrophysical Journal Supplement Series (ISSN
0067-0049), vol. 53, Dec. 1983, p. 869-892.
Publication Date: 12/1983
Category: Astrophysics
Origin: STI
NASA/STI Keywords: A STARS, B STARS, F STARS, LATE STARS, SHELL STARS,
STELLAR ENVELOPES, STELLAR SPECTRA, ULTRAVIOLET
ASTRONOMY, IUE, STELLAR MASS EJECTION, STELLAR
WINDS, ULTRAVIOLET SPECTRA
DOI: 10.1086/190912
Bibliographic Code: 1983ApJS...53..869S
Abstract
High-dispersion IUE spectra of 18 later type Be and A-F type shell stars
as well as eight standard nonemission line stars have been analyzed for
anomalous ionization and mass loss effects. It is found that
superionization in the Be stars extends to the latest spectral subtypes
but does not seem to be present in the A-F type stars. The superionized
lines in the Be stars appear to be correlated with v sin i. Asymmetrical
or violet-displaced resonance lines suggesting mass loss are observed in
all the Be stars except one, in some of the standard stars, but not in
the A-F stars. Lower limits to the mass loss rates computed from Si IV
lines range between 5.3 x 10 to the -12th and 3.5 x 10 to the -11th
solar masses/yr, with Be shell stars showing the largest values. Mass
loss is correlated with luminosity and effective temperature but not
with rotation.
Title: Research support for plasma diagnostics on Elmo
Bumpy Torus - development of a multichannel
Hall-probe based diamagnetic diagnostic instrument
and observation and modeling of EBT electron rings
Authors: Carpenter, K. H.; Booker, R. H.
Affiliation: Missouri Univ., Rolla.
Publication: Final Report, 1 Oct. 1982 - 30 Sep. 1983 Missouri
Univ., Rolla. Dept. of Electrical Engineering.
Publication Date: 10/1983
Category: Plasma Physics
Origin: STI
NASA/STI Keywords: BUMPY TORUSES, DIAMAGNETISM, FERROMAGNETIC
RESONANCE, HALL EFFECT, MAGNETIC PROBES,
MAGNETOMETERS, PLASMA DIAGNOSTICS, TOROIDAL PLASMAS,
CIRCUIT DIAGRAMS, COMPUTER PROGRAMS, CURRENT SHEETS,
HOT ELECTRONS, MAGNETIC FIELDS, RESONANCE PROBES
Bibliographic Code: 1983umo..rept.....C
Abstract
Use of multiple Hall effect probes is a cost effective way to observe
diamagnetic fields from the hot electron rings in the Elmo Bumpy Torus
device at several locations simultaneously. A special diagnostic
instrument was developed having six Hall probe chanels with the
sensitivity and stability needed for the diamagnetic measurements. The
instrument uses an AC carrier system with isolaton transformers located
remotely from the instrument and near the probe locations. Details of
instrument design as well as opera