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

• Published in: Astronomy and astrophysics (Berlin) Vol. 403; pp. 975 - 992
• Main Authors: Omont, A., Gilmore, G., Alard, C., Aracil, B., August, T., Baliyan, K., Blommaert, J., Borsenberger, J., Burgdorf, M., Cesarsky, C., de Batz, B., Egan, M., Egret, D., Epchtein, N., Felli, M., Fouque, P., Ganesh, S., Glass, I., Gredel, R., Groenewegen, M., Habing, H. J., Hennebelle, P., Jiang, B., Joshi, U., Messineo, M., Miville-Deschenes, M. A., Moneti, A., Ojha, D., Ortiz, R., Ott, S., Perault, M., Price, S., Robin, A., Schultheis, M., Schuller, F., Simon, Grégory, Testi, L., Teyssier, D., van Loon, J., Wyse, R.
• Format: Journal Article
• Language: English
• Published: EDP Sciences 2003
• Subjects: Astrophysics; Cosmology and Extra-Galactic Astrophysics; Physics
• ISSN: 0004-6361; 1432-0746

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 micron ISOCAM observations - with a resolution of 6\'\' at worst - with DENIS IJKs data to determine the nature of the sources and theinterstellar extinction. We have observed about 16 square degrees with a sensitivity approaching 10-20mJy, 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 description is given in Schuller et al. 2003, astro-ph/0304309): viz. the images and theISOGAL-DENIS five-wavelength point source catalogue. The main scientific results already derived or in progress are summarized. These include astrometrically calibrated 7 and 15um 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.