2003A&A...405..531S -
Astronomy and Astrophysics, volume 405, 531-550 (2003/7-2)
Near-IR spectra of ISOGAL sources in the inner Galactic Bulge.
SCHULTHEIS M., LANCON A., OMONT A., SCHULLER F. and OJHA D.K.
Abstract (from CDS):
We present near-IR spectra (HK-band) of a sample of 107 sources with mid-IR excesses at 7 and 15 µm detected during the ISOGAL survey. Making use of the DENIS interstellar extinction map from Schultheis et al. (
1999A&A...349L..69S) we derive luminosities and find that the M
bol vs.
12CO and M
bol vs. H
2O diagrams are powerful tools for identifying supergiants, AGB stars, giants and young stellar objects. The majority of our sample are AGB stars (∼80%) while we find four good supergiant candidates, nine young stellar objects and 12 RGB candidates. We have used the most recent K
0-[15] relation by Jeong et al. (2002, in Mass-losing Pulsating stars and their Circumstellar Matter, ed. Y. Nakasa, M. Honma, & M. Sekiin ) based on recent theoretical modeling of dust formation of AGB stars to determine mass-loss rates. The mass-loss rates of the supergiants are comparable with those in the solar neighbourhood while the long-period variables cover a mass-loss range from -5<log{dot}(M)←7. The red giant candidates lie at the lower end of the mass-loss rate range between -6.5<log{dot}(M)←9. We used the equivalent width of the CO bandhead at 2.3µm, the NaI doublet and the CaI triplet to estimate metallicities using the relation by Ramirez et al. (
2000AJ....120..833R). The metallicity distribution of the ISOGAL objects shows a mean [Fe/H]~-0.25dex with a dispersion of ±0.40dex which is in agreement with the values of Ramirez et al. (
2000AJ....120..833R) for Galactic Bulge fields between b=-4° and b=-1.3°. A comparison with the solar neighbourhood sample of Lancon & Wood (
2000A&AS..146..217L) shows that our sample is ∼0.5dex more metal-rich on average.
Abstract Copyright:
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Journal keyword(s):
infrared: stars - ISM: dust, extinction - Galaxy: bulge - stars: AGB and post-AGB
VizieR on-line data:
<Available at CDS (J/A+A/405/531): table1.dat spectra/*>
Nomenclature:
Table A1: [SLO2003] ANN N=107.
Simbad objects:
108
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