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

Abstract

In this work we present near-IR spectra (HK-band) of a sample of 107 sources with mid-IR excesses at 7 and 15 $\mu$m 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 ${\mathrm{M}}_{\mathrm{bol}}$ vs.~${}^{12}\mathrm{CO}$ and ${\mathrm{M}}_{\mathrm{bol}}vs.{\mathrm{H}}_2\mathrm{O}$ 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 ${\mathrm{K}}_0-[15]$ relation by Jeong et al. (2002) based on recent theoretical modeling of dust formation of AGB stars to determine mass-loss rates. However, the uncertainties in the mass-loss rates are rather large. 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 candidateslie 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 2.3 $\mu \mathrm{m}$, the NaI doublet and the CaI triplet to estimate metallicities using the relation by Ram\'ırez et al. (\cite{Ramirez2000}). The metallicity distribution of the ISOGAL objects shows a mean [Fe/H] $\sim$ -0.25 dex with a dispersion of $\pm 0.40dex$ which is in agreement with the values of Ramírez et al. (\cite{Ramirez2000}) for Galactic Bulge fields between $\mathrm{b}=-4^{\mathrm{o}}$ and $\mathrm{b}=-1.3^{\mathrm{o}}$. A comparison with the solar neighbourhood sample of Lançon & Wood (LW) shows that our sample is ~ 0.5 dex more metal-rich on average.

arXiv comment23 pages, 9 figures, 2 appendix with IR spectra. accepted for A&A

References in corpus (20)

• Infrared stellar populations in the central parts of the Milky Way galaxy
• A revision of the solar neighbourhood metallicity distribution
• Stellar Iron Abundances at the Galactic Center
• The Outer Regions of the Galactic Bulge:II Analysis
• The MACHO Project 9 Million Star Color-Magnitude Diagram of the Large Magellanic Cloud
• ISOGAL: A deep survey of the obscured inner Milky Way with ISO at 7 and 15 micron and with DENIS in the near-infrared
• ISOCAM observations of Galactic Globular Clusters: mass loss along the Red Giant Branch
• An Accurate, Easy to Use Abundace Scale for Globular Clusters Based on 2.2um Spectra of Giant Stars
• Metallicity of Red Giants in the Galactic Bulge from Near-Infrared Spectroscopy
• Implications of New JHK Photometry and a Deep Infrared Luminosity Function for the Galactic Bulge
• The Metallicity and Reddening of Stars in the Inner Galactic Bulge
• 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-infrared Spectra of Chamaeleon I Stars
• Bulges
• Stellar sources in the ISOGAL intermediate bulge fields
• M giants in Macho, DENIS and Isogal
• Low resolution spectroscopy of ISOGAL sources: Search for early-type stars with infrared excess

Cited by in corpus (26)

• Target Selection for the Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• Chemical tagging with APOGEE: Discovery of a large population of N-rich stars in the inner Galaxy
• Tracing the long bar with red-clump giants
• ISOGAL: A deep survey of the obscured inner Milky Way with ISO at 7 and 15 micron and with DENIS in the near-infrared
• Recent star formation in the inner Galactic Bulge seen by ISOGAL II -- The Central Molecular Zone
• Massive Young Stellar Objects in the Galactic Center. I. Spectroscopic Identification from Spitzer/IRS Observations
• Kinematic Detection of the Galactic Nuclear Disc
• The Mass-Loss Return from Evolved Stars to the Large Magellanic Cloud II: Dust Properties for Oxygen-Rich Asymptotic Giant Branch Stars
• Interstellar Extinction and Long-Period Variables in the Galactic Center
• Discovery of new Milky Way star cluster candidates in the 2MASS point source catalog III. Follow-up observations of cluster candidates in the Galactic Center region
• Evidence for a metal-poor population in the inner Galactic Bulge
• 86 GHz SiO maser survey of late-type stars in the Inner Galaxy II. Infrared photometry of the SiO Target Stars
• Cool stars in the Galactic Center as seen by APOGEE: M giants, AGB stars and supergiant stars/candidates
• Late-type giant variables in NGC6522, LMC and SMC: How do they differ?
• First Spectroscopic Identification of Massive Young Stellar Objects in the Galactic Center
• The most metal-rich stars in the universe: chemical contributions of low and intermediate mass asymptotic giant branch stars with metallicities between $0.04\le Z\le \mathrm{0.10.}$
• A global view on star formation: The GLOSTAR Galactic plane survey IV. Radio continuum detections of young stellar objects in the Galactic Centre region
• Temperatures and metallicities of M giants in the galactic Bulge from low-resolution K-band spectra
• Near-infrared spectroscopic observations of massive young stellar object candidates in the Central Molecular Zone
• Accurate OH maser positions II. the Galactic Center region
• A search for late-type supergiants in the inner regions of the Milky Way
• Recent star formation in the inner Galactic Bulge seen by ISOGAL. I - Classification of bright mid-IR sources in a test field
• Metallicity distribution of red giants in the Inner Galaxy from Near Infrared spectra
• Near-IR spectroscopy of OH/IR stars in the Galactic Centre
• CO J = 2 - 1 Emission from Evolved Stars in the Galactic Bulge
• Stellar populations in a standard ISOGAL field in the Galactic disk