Stellar sources in the ISOGAL intermediate bulge fields

Abstract

We present a study of ISOGAL sources in the "intermediate" galactic bulge ($|$$l$$|$ $<$ 2${}^{\circ }$, $|$$b$$|$ $\sim$ 1${}^{\circ }$--4${}^{\circ }$), observed by ISOCAM at 7 and 15 $\hat{I}¼m$. In combination with near-infrared (I, J, K${}_{\mathrm{s}}$) 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 $\hat{I}¼m$ are AGB stars above the RGB tip, a number of them show an excess in ([7]-[15])${}_0$ and (K${}_{\mathrm{s}}$-[15])${}_0$ colours, characteristic of mass-loss. The latter, especially (K${}_{\mathrm{s}}$-[15])${}_0$, provide estimates of the mass-loss rates and show their distribution in the range 10${}^{-8}$ to 10${}^{-5}$ M${}_{\odot }$/yr.

16 pages, accepted for publication in Astronomy and Astrophysics