The ISOGAL field FC-01863+00035: Mid-IR interstellar extinction and stellar populations
Abstract
A 0.35 degr x 0.29 degr field centered at l=-18.63 degr, b=0.35 degr was observed during the ISOGAL survey by ISOCAM imaging at 7 mu m and 15 mu m. 648 objects were detected and their brightness are measured. By combining with the DENIS data in the near-infrared J and KS bands, one derives the extinction at 7 mu m through AK_S-A7 = 0.35 (AJ-AK_S) which yields A7/AV ~ 0.03 from the near-IR extinction values of van de Hulst-Glass (Glass \cite{Glass99}). The extinction structure along the line of sight is then determined from the values of J-KS or KS-[7] of the ISOGAL sources identified as RGB or early AGB stars with mild mass-loss. The distribution of AV ranges from 0 to ~ 45 and it reflects the concentration of the extinction in the spiral arms. Based on their locations in color-magnitude diagrams and a few cross-identifications with IRAS and MSX sources, the nature of objects is discussed in comparison with the case of a low extinction field in Baade's Window. Most of the objects are either AGB stars with moderate mass loss rate or luminous RGB stars. Some of them may be AGB stars with high mass loss rate. In addition, a few young stellar objects (YSOs) are present.
This is paper No. 15 in a journal based on data from the ISOGAL project. Based on observations with ISO, an ESA project with instruments funded by ESA Members States (especially the PI countries: France, Germany, The Netherlands and the UK) and with the participation of ISAS and NASA; and on DENIS observations collected at the European Southern Observatory, Chile. Table 5 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/400/903- Publication:
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Astronomy and Astrophysics
- Pub Date:
- March 2003
- DOI:
- 10.1051/0004-6361:20030004
- arXiv:
- arXiv:astro-ph/0302411
- Bibcode:
- 2003A&A...400..903J
- Keywords:
-
- stars: AGB and post-AGB;
- stars: late-type;
- stars: mass loss;
- stars: pre-main sequence;
- ISM: dust;
- extinction;
- Galaxy: stellar content;
- Infrared: stars;
- Astrophysics
- E-Print:
- 14 pages, accepted for publication in Astronomy and Astrophysics