Detailed Abundances in the Galactic Center: Evidence of a Metal-rich Alpha-enhanced Stellar Population
Journal
Date Issued
2020
Author(s)
Thorsbro, B.
•
Ryde, N.
•
Rich, R. M.
•
Schultheis, M.
•
Renaud, F.
•
Spitoni, E.
•
Fritz, T. K.
•
Mastrobuono-Battisti, A.
•
•
Matteucci, F.
•
Schödel, R.
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 spectrograph 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 α-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 compositions.
Volume
894
Issue
1
Start page
26
Issn Identifier
0004-637X
Ads BibCode
2020ApJ...894...26T
Rights
open.access
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