1998/03/24 by T. J. Davidge · 3 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/300365
29 pages, including 14 figures
arxiv created 1998/03/24 · openalex publication_date 1998/06/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
Images recorded through broadband ( JHK ) and narrowband (CO and 2.2 μm continuum) filters are used to investigate the photometric properties of bright ( K ≤ 13.5) stars in a 6' × 6' field centered on the Sgr A complex. The giant branch ridge lines in the ( K , J - K ) and ( K , H - K ) color-magnitude diagrams are well matched by the Baade's window (BW) M giant sequence if the mean extinction is A K ∼ 2.8 mag. Extinction measurements for individual stars are estimated using the M K versus infrared color relations defined by M giants in BW, and the majority of stars have A K between 2.0 and 3.5 mag. The extinction is locally high in the Sgr A complex, where A K ∼ 3.1 mag. Reddening-corrected CO indexes, CO 0 , are derived for over 1300 stars with J , H , and K brightnesses and for over 5300 stars with H and K brightnesses. The distribution of CO 0 values for stars with K 0 between 11.25 and 7.25 can be reproduced using the M K -CO 0 relation defined by M giants in BW. The data thus suggest that the most metal-rich giants in the central regions of the bulge and in BW have similar photometric properties and 2.3 μm CO strengths. Hence, it appears that the central region of the bulge does not contain a population of stars that are significantly more metal-rich than what is seen in BW.