Anthony Marston

Herschel Instrument and Calibration Scientist (HIFI) - ESA.

27 September 2006

I joined ESA in 2003 (ESTEC) after working in the US for 15 years -
my last institution being IPAC, Caltech at the Spitzer Science
Center. I have been at ESAC for a little more than a year. My
current position involves working with the HIFI instrument
development and includes significant time at the instrument
building site in Groningen, The Netherlands.

My main scientific interest for many years has been the study of
evolved massive stars, and in particular Wolf-Rayet stars.
Wolf-Rayet stars are believed to have evolved from O stars with an
initial mass greater than 20 solar masses. There are relatively few
known in the galaxy (230 or so) yet their very strong winds and
high luminosities have a significant effect on their surroundings
and what they tell us about extragalactic star formation processes
(e.g., the so-called Wolf-Rayet galaxies).

Problem: 
Understanding massive star evolution: there are few known and they
evolve fast (few million years).
1. Common belief that such stars formed in Giant Molecular Clouds
   (GMCs). But many Wolf-Rayet stars found well away from GMCs.
   Where are they born? 
2. We only know a few hundred we would expect thousands to exist in
   our galaxy - are we just seeing an observational bias? 
3. How can we improve our knowledge of their evolution? What can
   their surroundings tell us?

Currently associated with two major projects in these regards.
a. To find the distribution of evolved massive stars in the galaxy
   - particularly Wolf-Rayet stars (so far found another 23 in the
   last year of work - and half appear to NOT be in molecular
   clouds).
b. To study the interaction of these stars with their environments
   (approved Spitzer and Akari projects).