EDP Sciences
Free access
Volume 403, Number 1, May III 2003
Page(s) 141 - 154
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20030208

A&A 403, 141-154 (2003)
DOI: 10.1051/0004-6361:20030208

Stellar sources in the ISOGAL intermediate bulge fields

D. K. Ojha1, A. Omont2, F. Schuller2, G. Simon3, S. Ganesh4 and M. Schultheis2

1  Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India
2  Institut d'Astrophysique de Paris, CNRS, 98bis Bld. Arago, 75014 Paris, France
    e-mail: omont@iap.fr
3  GEPI, Observatoire de Paris, 61 Av. de l'Observatoire, 75014, Paris, France
4  Physical Research Laboratory, Navarangpura, Ahmedabad 380009, India

(Received 3 June 2002 / Accepted 11 February 2003 )

We present a study of ISOGAL sources in the "intermediate" galactic bulge ( $\vert l\vert< 2^\circ$, $\vert b\vert\sim 1^\circ$-4°), observed by ISOCAM at 7 and 15  $\mu$m. In combination with near-infrared ( I, J, $K_{\rm s}$) 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]) $_{\rm0}$ and ( $K_{\rm s}$-[15]) $_{\rm0}$ colours, characteristic of mass-loss. The latter, especially ( $K_{\rm s}$-[15]) $_{\rm0}$, provide estimates of the mass-loss rates and show their distribution in the range 10-8 to 10 $^{-5}~M_{\odot}$ yr -1.

Key words: stars: AGB and post-AGB -- stars: circumstellar matter -- stars: mass-loss -- dust: extinction -- infrared: stars -- Galaxy: bulge

Offprint request: D. K. Ojha, ojha@tifr.res.in

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