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Within the past few years, great progress has been made towards our
understanding of the astrophysical role played by massive stars. From
an observational perspective, temperatures of OB stars have been
revised downward based on the most recent observations with FUSE, HST
and ground-based facilities; the role of clumping in stellar winds
has been recognized, with potentially dramatic consequences for
stellar evolution, due to its influence on derived mass-loss rates;
close binaries with masses of up to 80 solar masses have been
identified and studied visually and with exquisite detail using
Chandra, XMM, VLA; visibly obscured young massive clusters have been
identified at our Galactic Centre, elsewhere in our own Milky Way and
in external galaxies. These have been studied with HST, VLT, Gemini
and Subaru, exploiting natural guide star Adaptive Optics (AO)
techniques from the ground. Increasingly the use of AO with laser
guide stars is expected to revolutionise the study of massive star
forming regions.
Quantitative spectroscopy of massive stars beyond the Local Group has
been undertaken with VLT and Keck to disentangle chemical evolution
of galaxies in the nearby Universe and to determine independent
distances; star formation histories have been inferred from
population/spectrum ynthesis of resolved/unresolved populations of
nearby star forming galaxies; nearby starbursts – templates for high
redshift counterparts - have been studied with FUSE, HST, GALEX and
Spitzer. Large surveys for star forming galaxies from redshifts 1 to
6, making use of colour selection techniques at optical, infrared and
sub-mm wavelengths, have provided quantitative measures of their
massive stellar populations over most of the age of the universe,
including their past history of star formation, the IMF, assembled
stellar masses, metallicities and chemical yields; from space, HETE
and SWIFT have allowed an increasing number of GRBs to be studied in
detail, with rapid follow-up from ground-based facilities permitting
chemical information on their host galaxies to be obtained. These are
all tremendously exciting topics, at the forefront of present-day
astrophysical research and providing some of the core scientific
cases for the next generation of extremely large telescopes currently
under development.
Theoretically, great advances have been made towards improved
evolutionary and atmospheric models for massive stars allowing for
rotation and magnetic fields, and towards the evolution of massive
binary systems; the impact of internal waves generated at the
boundary of the convective core on the transport of angular momentum
and chemical species in the stellar interior; important developments
have taken place with respect to spectral synthesis of starbursts,
improved spectral energy distributions of young stellar populations,
hydrodynamic simulations of GRB explosions, and notably numerical
simulations of star formation at the earliest epochs, including very
massive Population III stars which are thought to play the dominant
role in the reionization of the universe at redshift z > 6.
The key astrophysical problems for the symposium are:
- Atmospheres of massive stars;
- Physics and evolution of massive stars;
- Massive stellar populations in the nearby Universe;
- Hydrodynamics and feedback from massive stars in galaxy evolution;
- Massive stars as probes of the early Universe.
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