Stellar populations in a standard ISOGAL field in the Galactic disk

Abstract

We aim to identify the stellar populations (mostly red giants and young stars) detected in the ISOGAL survey at 7 and 15micron towards a field (LN45) in the direction l=-45, b=0.0. The sources detected in the survey of the Galactic plane by the Infrared Space Observatory are characterized based on colour-colour and colour-magnitude diagrams. We combine the ISOGAL catalog with the data from surveys such as 2MASS and GLIMPSE. Interstellar extinction and distance are estimated using the red clump stars detected by 2MASS in combination with the isochrones for the AGB/RGB branch. Absolute magnitudes are thus derived and the stellar populations are identified based on their absolute magnitudes and their infrared excess. A standard approach to the analysis of ISOGAL disk observations has been established. We identify several hundred RGB/AGB stars and 22 candidate young stellar objects in the direction of this field in an area of 0.16 deg^2. An over-density of stellar sources is found at distances corresponding to the distance of the Scutum-Crux spiral arm. In addition, we determine mass-loss rates of AGB-stars using dust radiative transfer models from the literature.

48pages, 38 figures, accepted for publication in A & A

References in corpus (22)

• The Spitzer Space Telescope Mission
• GLIMPSE: I. A SIRTF Legacy Project to Map the Inner Galaxy
• The Wavelength Dependence of Interstellar Extinction from 1.25 to 8.0 microns Using GLIMPSE Data
• Modelling the Galactic Interstellar Extinction Distribution in Three Dimensions
• A three-dimensional Galactic extinction model
• First GLIMPSE Results on the Stellar Structure of the Galaxy
• Infrared Extinction Toward Nearby Star-Forming Regions
• Old stellar Galactic disc in near-plane regions according to 2MASS: scales, cut-off, flare and warp
• The MACHO Project: 45 Candidate Microlensing Events from the First Year Galactic Bulge Data
• The mid- and far-infrared colours of AGB and post-AGB stars
• ISOGAL: A deep survey of the obscured inner Milky Way with ISO at 7 and 15 micron and with DENIS in the near-infrared
• Extinction within 10 degrees of the Galactic Centre using 2MASS
• The Infrared Extinction Law at Extreme Depth in a Dark Cloud Core
• Mass-Losing Semiregular Variable Stars in Baade's Windows
• ISOGAL Survey of Baade's Windows in the Mid-infrared
• Young massive stars in the ISOGAL survey II. The catalogue of bright YSO candidates
• Explanatory Supplement of the ISOGAL-DENIS Point Source Catalogue
• Near-IR spectra of ISOGAL sources in the Inner Galactic Bulge
• Extinctions at 7um and 15um from the ISOGAL survey
• Stellar sources in the ISOGAL intermediate bulge fields
• The ISOGAL field FC--01863+00035: Mid-IR interstellar extinction and stellar populations
• Recent star formation in the inner Galactic Bulge seen by ISOGAL. I - Classification of bright mid-IR sources in a test field