Stellar sources in the ISOGAL intermediate bulge fields

Abstract

We present a study of ISOGAL sources in the "intermediate" galactic bulge (|l| < 2°, |b| ∼ 1°-4°), observed by ISOCAM at 7 and 15 µm. 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 µm are AGB stars above the RGB tip, a number of them show an excess in ([7]–[15])₀and (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_⊙ yr⁻¹.