Stellar sources in the ISOGAL intermediate bulge fields

Abstract

We present a study of ISOGAL sources in the ``intermediate'' galactic bulge (|l|< 2^o, |b| ~ 1^o-4^o), observed by ISOCAM at 7 and 15 mu m. In combination with near-infrared (I, J, K_s) data of DENIS survey, complemented by 2MASS data, we discuss the nature of the ISOGAL sources, their luminosities, the interstellar extinction and the mass-loss rates. A large fraction of the 1464 detected sources at 15 mu m are AGB stars above the RGB tip, a number of them show an excess in ([7]-[15])₀ and (K_s-[15])₀ colours, characteristic of mass-loss. The latter, especially (K_s-[15])₀, provide estimates of the mass-loss rates and show their distribution in the range 10^-8 to 10^-5 M_sun yr^-1.

This is paper No. 14 in a refereed journal based on data from the ISOGAL project.

Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands and the UK) and with the participation of ISAS and NASA.

Based on observations collected at the European Southern Observatory, La Silla, Chile.