Contents of: VI/111/./abstract/AOMONT_ISOGAL7P.abs

The following document lists the file abstract/AOMONT_ISOGAL7P.abs from catalogue VI/111.
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==> In this proposal, more time is being requested for AOMONT.ISOGALIN
==> This proposal requests an upgrade from Priority 3 for AOMONT.ISOGALIN
ISOGAL is the first detailed mid-IR imaging survey of the inner Galaxy, tracing
Galactic structure and stellar populations. It combines 7-15mu data with the IJK
DENIS survey which has already completely observed the ISOGAL fields. We have
three main goals: trace the large scale disk structure using primarily red giant
(gM) old stars; detect many dusty young stars and map the ISM star formation
regions through diffuse emission and extinction; study the stellar populations
and the structure of the bulge. The central regions of the Milky Way contain the
most extreme stellar cluster known, the majority of the stellar mass, most of
the spiral structure, much of the star formation, the disk bar, the mysterious
central bulge, the molecular ring, and many examples of rare and extreme stellar
and dynamical states. Most of these are confused in projection and are heavily
obscured even in the near-IR. Multi-colour mid-IR data are essential to analyse
these features. ISOGAL quantifies the distribution of the stellar populations,
especially of young dusty, old (gM), and AGB, stars, of low luminosity
star-formation regions, UCHII regions, and both diffuse and dense interstellar
material. The 70 hours allocated and successfully observed have, as proposed,
been devoted almost exclusively to 15mu observations, to maximise originality
with respect to ground near-IR (half our 15mu sources seem to be dusty YSOs not
detectable at IJK) and avoid saturation. Our first ISOGAL results combined with
DENIS provide adequate photometry and extinction on gMs at several kpc, as well
as two major results beyond our expectations: we see even more young, low-mass
stars and very many more extremely high-extinction clouds than expected. Besides
the many major goals already achievable with these 15mu data alone, the addition
of a 2nd mid-IR color (7mu), now proved technically feasible, will be a decisive
gain : increase the sample of detected distant gMs by a factor 5, essential to
reliably trace galactic structure; improve study of diffuse emission; confirm
and characterise the many dusty YSOs only detected at 15mu; improve the
reliability of characterisation of all stars, and the extinction.

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