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<b>Stellar Winds, Outflowing Disks and Mass Loss:</b>
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<p><img src="http://www.astro.uu.nl/siu/edu/img_0694.jpg"  border="0">
<p> Prof.dr. H.J.G.L.M. Lamers    
<br><br>
<font color="A52A2A"><strong>
<H1>Stellar Winds, Outflowing Disks and Mass Loss</H1></font></strong>

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<p>
<font color="010595"><strong><H2>Introduction</H2></strong></font>


<p>
During the last thirty years astronomers have discovered that nearly
all stars are losing mass in the form of stellar winds
through a major fraction of their lives.
This mass loss affects their evolution from their origin to their
death. 
It also leads to spectacular interactions between the supersonic stellar winds
and the interstellar medium in the form of planetary nebulae and
ring nebulae and in the form of interstellar bubbles and superbubbles.
The return of matter from stars into the interstellar medium
and the formation of bubbles and superbubbles changes the
chemical composition of the galaxies and affects their kinematical
properties.
<p>
Most types of stars eject mass in a spherically symmetric stellar wind.
However several special types of stars eject their matter in the form
of an equatorial disk. These are the rapid rotating Be-stars
and the B[e] supergiant stars. Rotation plays a role in the formation
of these outflowing disks. However centrifugal forces alone can not explain 
the observed properties, such as velocity, density and thickness.
<br>
<br><br>
<p>
<H2><font color="010595">Research in the Mdot group</font></H2>
<p>We study many aspects of stellar winds and outflowing disks, both
observationally and theoretically. Most of these in collaboration
with international colleagues.

<p><B>Hot topics that we are working on (2004):</B><br>
<UL>
<li> Explain the high mass loss rates of Wolf Rayet Stars:
<B>Lamers</B> and Nugis (Tartu)
<li> Spitzer IR observations of WR-stars: Cassinelli (Madison) and <B>Lamers</B>
<li> The evolutionary phase of unclassified B[e] stars: <B>Fernandes</B>, <B>Kraus</B>,
 Araujo (Rio de Janeiro), <B>Lamers</B>
<li> Properties of disks of B[e] supergiants: <B>Kraus</B>, <B>Lamers</B>
<li> Mass ejections from Nova Cygni 1982: Cassatella (Rome) and <B>Lamers</B>
<li> The effects of winds from star clusters on the interstellar
medium: <B>Stegeman</B>, Walder (Tucson), Mellema, <B>Lamers</B>
<li> Chandra observations of X-rays from supergiants: Cassinelli
(Madison), Waldron (Baltimore), <B>Lamers</B>
<li> Wolf Rayet central stars of Planetary Nebulae: Balick (Seattle)
 and <B>Lamers</B>
<li> Rotationally flattened winds of AGB stars and the shaping of 
Planetary Nebulae: <B>Lamers</B> and Balick (Seattle)
</UL>
 

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<br><br>
<p><B><H2><font color="010595">Composition of the Mdot group:</font></H2></B>
<dl>
<dt>Permanent staff: Henny Lamers (lamers@astro.uu.nl)
<dt>Postdoc: Michaela Kraus (kraus@astro.uunl)
<dt>PhD students: Marcelo Borges (borges@on.br)
<dt> Students: none at the moment
<dt>Former PhD students: Rens Waters, Norman Trams, Lex Kaper, Alex de
 Koter, Eric Bakker, Lucky Achmad, Robert Voors, Jeroen van Gent,
 Jorick Vink,  Willem-Jan de Wit, Marielle Stegeman
</dl>

<center>
<IMG SRC="img/mdot94.jpg" width="600" border="0">
<p><B>WADLOOP Expedition 1994.</B> Last row: Jeroen van Gent, Lucky Achmad,
Sander Slijkhuis, Alex de Koter, Henny Lamers. First row: Rene
Noordhoek, Robert Voors, Henrik Spoon, Ria de Koter, Linda Achmad.
 <p>
<IMG SRC="img/wwad.jpg" width="600" border="0">
<p><B>WADLOOP Expedition 2002.</B>  Willem Wad, Henny Lamers, Michaela Kraus,
Marcelo Borges, Pui-Kei Fung.
</center>

<br>
 <p><font color="010595"><H2><B>Publications</B></H2></font>
<A HREF="http://www.astro.uu.nl/siu/publ-lamers.html">ADS Abstract Service</A>
 <br>
<br><br>
<p>
<font color="010595"><H2><B>Lectures</B></H2> </font>
<p>
<DL>
<DT><B>Utrecht University</B>
  <DD> "Stellar Winds and Mass Loss"
    (lit: "Introduction to Stellar Winds" by Lamers and Cassinelli).
    This master course is given every other year, the next one in the
  Fall of 2005
  </DT></DD>
<DD>   "Introduction to Astrophysics"
    (lit: syllabis by Henny Lamers or Frank Verbunt).
    This bachelor course is given every Spring by either Lamers or Verbunt
</DD>
<DT><B>University College Utrecht</B>
<DD>   "Astrophysics"
    (lit: "Modern Astrophysics" by Carroll and Ostlie).
    This bachelor course is given every Fall by Lamers and Achterberg
   </DT></DD>
<DT><B>High Education for Adults (HOVO)</B>
 <DD>   Every year a different topic: e.g. Explosions in the universe,
 Compact objects, etc. This course is given every year by Lamers, 
Achterberg, Pols, Rutten, Hoyng, Heise</DD></DT>
</DT>
<DT><B>NOVA Fall school</B>
<DD>    "Stellar winds and mass loss".
     This graduate course is given every other year
</DD></DT>
</DL>

<br><br>

<p>
<font color="010595"><B><H2>Conferences organised in 2004/2005</H2></B></font>
  
    <p>
 "Massive Stars: from photospheres to V_infinity"
 a workshop to honour the scientific career of Joseph P. Cassinelli
 Sept 17-18, 2004, Madison (USA), 
 <a href="http://www.astro.wisc.edu" target="page">page</a> 

<p>
 "B[e] supergiants and unclassified B[e] stars"
  July 10-16, 2005, Vlieland (The Netherlands)
  info: <a href="mailto:kraus@astro.uu.nl">kraus@astro.uu.nl</a>
<p>
  "Mass loss and evolution at low metallicity"
   August 16-20, 2005, Tartu (Estonia)
   info: <a href="mailto:lamers@astro.uu.nl">lamers@astro.uu.nl</a>  or
   <a href="mailto:nugis@aai.ee">nugis@aai.ee</a> 

<br><br>
<p><a href="hl-res2.html">Star Clusters in Normal and Interacting
Galaxies</a><br>
</p>
<A target="extern" HREF="http://www.astro.uu.nl/siu/people.html"><font
color="marroon"><H2>Contact</H2></font></A>
</font></td></table>


<p>&nbsp;

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