EDP Sciences
Free access
Issue
A&A
Volume 403, Number 3, June I 2003
Page(s) 975 - 992
Section Stellar clusters and associations
DOI http://dx.doi.org/10.1051/0004-6361:20030437


A&A 403, 975-992 (2003)
DOI: 10.1051/0004-6361:20030437

ISOGAL: A deep survey of the obscured inner Milky Way with ISO at 7 $\mu$m and 15 $\mu$m and with DENIS in the near-infrared

A. Omont1, G. F. Gilmore2, C. Alard3, 1, B. Aracil1, T. August1, K. Baliyan4, S. Beaulieu2, 5, S. Bégon1, X. Bertou1, J. A. D. L. Blommaert6, 7, J. Borsenberger1, 8, M. Burgdorf6, 9, B. Caillaud1, C. Cesarsky10, A. Chitre1, 11, E. Copet12, B. de Batz3, M. P. Egan13, D. Egret14, N. Epchtein15, M. Felli16, P. Fouqué17, S. Ganesh1, 4, R. Genzel18, I. S. Glass19, R. Gredel20, M. A. T. Groenewegen7, F. Guglielmo1, H. J. Habing21, P. Hennebelle22, B. Jiang23, U. C. Joshi4, S. Kimeswenger24, M. Messineo21, M. A. Miville-Deschênes22, A. Moneti1, M. Morris25, D. K. Ojha26, 1, R. Ortiz21, 27, S. Ott6, 28, M. Parthasarathy29, M. Pérault22, S. D. Price13, A. C. Robin30, M. Schultheis1, F. Schuller1, G. Simon3, A. Soive1, L. Testi16, D. Teyssier22, D. Tiphène12, M. Unavane2, J. T. van Loon2, 31 and R. Wyse32

1  Institut d'Astrophysique de Paris, CNRS, 98 bis Bd. Arago, 75014 Paris
2  Institute of Astronomy, Cambridge, UK
3  GEPI, Observatoire de Paris, France
4  Physical Research Laboratory, Ahmedabad, India
5  University of Victoria, Canada
6  ISO Data Centre, ESA, Villafranca, Spain
7  Instituut voor Sterrenkunde, K. U. Leuven, Belgium
8  UMS-CNRS 2201, Observatoire de Paris, France
9  SIRTF Science Center, California Institute of Technology, Pasadena, CA, USA
10  ESO, Garching, Germany
11  Indian Institute of Science, Bangalore, India
12  LESIA, Observatoire de Paris, France
13  Air Force Research Laboratory, Hanscom AFB, MA, USA
14  Observatoire de Strasbourg, France
15  OCA, Nice, France
16  Osservatorio Astrofisico di Arcetri, Firenze, Italy
17  ESO, Santiago, Chile
18  MPIE, Garching, Germany
19  South African Astronomical Observatory, South Africa
20  Max-Planck Institut für Astronomie, Heidelberg, Germany
21  Leiden Observatory, Leiden, The Netherlands
22  Laboratoire de radioastronomie millimétrique, École Normale Supérieure and Observatoire de Paris, Paris, France
23  Department of Astronomy, Beijing Normal University, Beijing, China
24  Institut für Astrophysik der Leopold-Franzens, Universität Innsbruck, Austria
25  UCLA, Los Angeles, CA, USA
26  TIFR, Mumbai, India
27  UFES, Vitoria, Brasil
28  ESTEC, ESA, Noordwijk, The Netherlands
29  Indian Institute of Astrophysics, Bangalore, India
30  Observatoire de Besançon, France
31  Astrophysics Group, School of Chemistry & Physics, Keele University, UK
32  The Johns Hopkins University, Baltimore MD, USA



(Received 19 August 2002 / Accepted 17 March 2003)

Abstract
The ISOGAL project is an infrared survey of specific regions sampling the Galactic Plane selected to provide information on Galactic structure, stellar populations, stellar mass-loss and the recent star formation history of the inner disk and Bulge of the Galaxy. ISOGAL combines 7 and 15  $\mu$m ISOCAM observations - with a resolution of 6 $\arcsec$ at worst - with DENIS $IJK_{\rm s}$ data to determine the nature of the sources and the interstellar extinction. We have observed about 16 square degrees with a sensitivity approaching 10-20 mJy, detecting ~10 5 sources, mostly AGB stars, red giants and young stars. The main features of the ISOGAL survey and the observations are summarized in this paper, together with a brief discussion of data processing and quality. The primary ISOGAL products are described briefly (a full desciption is given in Schuller et al. 2003): viz. the images and the ISOGAL-DENIS five-wavelength point source catalogue. The main scientific results already derived or in progress are summarized. These include astrometrically calibrated 7 and 15  $\mu$m images, determining structures of resolved sources; identification and properties of interstellar dark clouds; quantification of the infrared extinction law and source dereddening; analysis of red giant and (especially) AGB stellar populations in the central Bulge, determining luminosity, presence of circumstellar dust and mass-loss rate, and source classification, supplemented in some cases by ISO/CVF spectroscopy; detection of young stellar objects of diverse types, especially in the inner Bulge with information about the present and recent star formation rate; identification of foreground sources with mid-IR excess. These results are the subject of about 25 refereed papers published or in preparation.


Key words: stars: AGB and post-AGB -- stars: circumstellar matter -- stars: mass-loss -- stars: formation -- dust: extinction -- infrared: stars -- Galaxy: bulge

Offprint request: A. Omont, omont@iap.fr

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