------------------------------------------------------------------------
From: Frederic Schuller  schuller@mpifr-bonn.mpg.de 
To: gcnews@aoc.nrao.edu
Subject: submit m027.tex A&A, accepted

%astro-ph/0603576

\begin{document}

\title{Recent star formation in the inner Galactic Bulge seen
by ISOGAL
}


\author{F. Schuller\inst{1,2} \and A. Omont\inst{1} \and I. S. 
Glass\inst{3}
\and M. Schultheis\inst{1,4} \and M. P. Egan\inst{5} \and S. D. 
Price\inst{6}}


\institute{
Institut d'Astrophysique de Paris, CNRS and Paris-VI University,
98 bis, Bd Arago, F-75014 Paris, France
\and
Max Planck Institut f\"ur Radioastronomie, Auf dem H\"ugel 69,
DE-53121 Bonn, Germany
\and
South African Astronomical Observatory, PO Box 9, Observatory 7935, South
Africa
\and
Observatoire de Besan\c{c}on, CNRS, 41 bis, av. de l'Observatoire,
B.P. 1615, F-25010 Besan\c{c}on Cedex, France
\and
Air Force Research Laboratory, ODASD, 1851 s. Bell St., CM3,
Suite 7000, Arlington, VA 22202, USA
\and
Air Force Research Laboratory, Space Vehicles Directorate, 29 Randolph 
Road,
Hanscom AFB, MA 01731, USA
}


\abstract{The stellar populations in the central region of the Galaxy
are poorly known because of the high visual extinction and very
great source density in this direction.}
{To use recent infrared surveys for studying the dusty stellar objects
in this region.}
{We analyse the content of a $\sim20\times20$~arcmin$^2$ field centred at
$(l,b)=(-0.27\dd,-0.06\dd)$ observed at 7 and 15\mic ~as part of the
ISOGAL survey. These ISO observations are more than an order of magnitude
better in sensitivity and spatial resolution than the IRAS observations.
The sources are cross-associated with other catalogues to identify
various types of objects. We then derive criteria to distinguish
young objects from post-main sequence stars.}
{We find that a sample of about 50 young stellar objects and
ultra-compact \hii ~regions emerges, out of a population of evolved
AGB stars. We demonstrate that the sources colours and
spatial extents, as they appear in the ISOGAL catalogue, possibly
complemented with MSX photometry at 21\mic, can be used to determine
whether the ISOGAL sources brighter than 300~mJy at 15\mic ~(or
[15]$\leq$4.5~mag) are young objects or late-type evolved stars.}{}
\keywords{Galaxy:Centre - Stars:formation - Stars:variables:general -
Infrared:stars}


\maketitle