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

• Published in: Astronomy and astrophysics (Berlin) Vol. 403; no. 3; pp. 975 - 992
• Main Authors: Omont, A., Gilmore, G. F., Alard, C., Aracil, B., August, T., Baliyan, K., Beaulieu, S., Bégon, S., Bertou, X., Blommaert, J. A. D. L., Borsenberger, J., Burgdorf, M., Caillaud, B., Cesarsky, C., Chitre, A., Copet, E., de Batz, B., Egan, M. P., Egret, D., Epchtein, N., Felli, M., Fouqué, P., Ganesh, S., Genzel, R., Glass, I. S., Gredel, R., Groenewegen, M. A. T., Guglielmo, F., Habing, H. J., Hennebelle, P., Jiang, B., Joshi, U. C., Kimeswenger, S., Messineo, M., Miville-Deschênes, M. A., Moneti, A., Morris, M., Ojha, D. K., Ortiz, R., Ott, S., Parthasarathy, M., Pérault, M., Price, S. D., Robin, A. C., Schultheis, M., Schuller, F., Simon, G., Soive, A., Testi, L., Teyssier, D., Tiphène, D., Unavane, M., van Loon, J. T., Wyse, R.
• Format: Journal Article
• Language: English
• Published: EDP Sciences 01.06.2003
• Subjects: Astrophysics; dust: extinction; Galaxy: bulge; infrared: stars; Sciences of the Universe; stars: AGB and post-AGB; stars: circumstellar matter; stars: formation; stars: mass-loss
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361:20030437

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 μm ISOCAM observations – with a resolution of 6″ at worst – with DENIS IJKs 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 ~105 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 μm 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.