Near-IR spectra of ISOGAL sources in the inner Galactic Bulge

Open Access
Publisher Website
Google Scholar
Abstract
We present near-IR spectra (HK-band) of a sample of 107 sources with mid-IR excesses at 7 and 15m detected during the ISOGAL survey. Making use of the DENIS interstellar extinction map from Schultheis et al. (1999) we derive luminosities and find that the M bol vs. and 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 relation by Jeong et al. ([CITE]) 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 . The red giant candidates lie at the lower end of the mass-loss rate range between . We used the equivalent width of the CO bandhead at 2.3 , the NaI doublet and the CaI triplet to estimate metallicities using the relation by Ramírez et al. ([CITE]). The metallicity distribution of the ISOGAL objects shows a mean dex with a dispersion of which is in agreement with the values of Ramírez et al. ([CITE]) for Galactic Bulge fields between and . A comparison with the solar neighbourhood sample of Lançon & Wood ([CITE]) shows that our sample is ~0.5 dex more metal-rich on average.
All Related Versions