2003/07/15 by R. D. Blum, Robert Blum, Solange Ramírez +4 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/378380
published as Astrophys.J.597:323-346,2003 · ApJ, accepted. Latex, 65 pages including 19 figures
arxiv created 2003/07/15 · openalex publication_date 2003/10/17 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We present λ/Δλ = 550-1200 near-infrared H and K spectra for a magnitude-limited sample of 79 asymptotic giant branch and cool supergiant stars in the central ≈5 pc (diameter) of the Galaxy. We use a set of similar spectra obtained for solar neighborhood stars with known T eff and M bol that is in the same range as the Galactic center (GC) sample to derive T eff and M bol for the GC sample. We then construct the H-R diagram for the GC sample. Using an automated maximum likelihood routine, we derive a coarse star formation history of the GC. We find that (1) roughly 75% of the stars formed in the central few parsecs are older than 5 Gyr; (2) the star formation rate (SFR) is variable over time, with a roughly 4 times higher SFR in the last 100 Myr compared to the average SFR; (3) our model can match dynamical limits on the total mass of stars formed only by limiting the initial mass function to masses above 0.7 M ☉ (this could be a signature of mass segregation or of the bias toward massive star formation from the unique star formation conditions in the GC); (4) blue supergiants account for 12% of the total sample observed, and the ratio of red to blue supergiants is roughly 1.5; and (5) models with isochrones with [Fe/H] = 0.0 over all ages fit the stars in our H-R diagram better than models with lower [Fe/H] in the oldest age bins, consistent with the finding of Ramírez et al. that stars with ages between 10 Myr and 1 Gyr have solar [Fe/H].