TY - JOUR
T1 - Detailed Abundances in the Galactic Center
T2 - Evidence of a Metal-rich Alpha-enhanced Stellar Population
AU - Thorsbro, B.
AU - Ryde, N.
AU - Rich, R. M.
AU - Schultheis, M.
AU - Renaud, F.
AU - Spitoni, E.
AU - Fritz, T. K.
AU - Mastrobuono-Battisti, A.
AU - Origlia, L.
AU - Matteucci, F.
AU - Schödel, R.
PY - 2020
Y1 - 2020
N2 - 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.
AB - 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.
U2 - 10.3847/1538-4357/ab8226
DO - 10.3847/1538-4357/ab8226
M3 - Article
AN - SCOPUS:85088388608
SN - 0004-637X
VL - 894
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 26
ER -