B. Thorsbro, N. Ryde, R. M. Rich, M. Schultheis, F. Renaud, E. Spitoni, T. K. Fritz, A. Mastrobuono-Battisti, L. Origlia, F. Matteucci, R. Schödel
Detailed abundances in the Galactic center: Evidence of a metal-rich alpha-enhanced stellar population
See arXiv version
13 pages, 10 figures, accepted for publication in ApJ, Figure 7 corrected
Abstract
We present a detailed study of the composition of 20 M giants in the Galactic center with 15 of them confirmed to be in the Nuclear Star Cluster. As a control sample we have also observed 7 M giants in the Milky Way Disk with similar stellar parameters. All 27 stars are observed using the NIRSPEC spectograph on the KECK II telescope in the K-band at a resolving power of R=23,000. We report the first silicon abundance trends versus [Fe/H] for stars in the Galactic center. While finding a disk/bulge like trend at subsolar metallicities, we find that [Si/Fe] is enhanced at supersolar metallicities. We speculate on possible enrichment scenarios to explain such a trend. However, the sample size is modest and the result needs to be confirmed by additional measurements of silicon and other \textalpha-elements. We also derive a new distribution of [Fe/H] and find the most metal rich stars at [Fe/H]=+0.5 dex, confirming our earlier conclusions that the Galactic center hosts no stars with extreme chemical composition.
amalie@auriga:~/Nextcloud/Uddannelse/UNI/phd/iSIMBA/isimbadk/htmlrequests$ python3 arxivposts.py 2003.11085
B. Thorsbro, N. Ryde, R. M. Rich, M. Schultheis, F. Renaud, E. Spitoni, T. K. Fritz, A. Mastrobuono-Battisti, L. Origlia, F. Matteucci, R. Schödel
Detailed abundances in the Galactic center: Evidence of a metal-rich alpha-enhanced stellar population
See arXiv version
13 pages, 10 figures, accepted for publication in ApJ, Figure 7 corrected
Abstract
We present a detailed study of the composition of 20 M giants in the Galactic center with 15 of them confirmed to be in the Nuclear Star Cluster. As a control sample we have also observed 7 M giants in the Milky Way Disk with similar stellar parameters. All 27 stars are observed using the NIRSPEC spectograph on the KECK II telescope in the K-band at a resolving power of R=23,000. We report the first silicon abundance trends versus [Fe/H] for stars in the Galactic center. While finding a disk/bulge like trend at subsolar metallicities, we find that [Si/Fe] is enhanced at supersolar metallicities. We speculate on possible enrichment scenarios to explain such a trend. However, the sample size is modest and the result needs to be confirmed by additional measurements of silicon and other \textalpha-elements. We also derive a new distribution of [Fe/H] and find the most metal rich stars at [Fe/H]=+0.5 dex, confirming our earlier conclusions that the Galactic center hosts no stars with extreme chemical composition.
