Detailed Abundances in the Galactic Center: Evidence of a Metal-rich Alpha-enhanced Stellar Population

DOI: 
10.3847/1538-4357/ab8226
Publication date: 
01/05/2020
Main author: 
Thorsbro, B.
IAA authors: 
Schödel, R.
Authors: 
Thorsbro, B.;Ryde, N.;Rich, R. M.;Schultheis, M.;Renaud, F.;Spitoni, E.;Fritz, T. K.;Mastrobuono-Battisti, A.;Origlia, L.;Matteucci, F.;Schödel, R.
Journal: 
The Astrophysical Journal
Refereed: 
Yes
Publication type: 
Article
Volume: 
894
Pages: 
26
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.
Database: 
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2020ApJ...894...26T/abstract
ADS Bibcode: 
2020ApJ...894...26T
Keywords: 
Astrophysics - Astrophysics of Galaxies;Astrophysics - Solar and Stellar Astrophysics