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

Thorsbro, B. LU orcid ; Ryde, N. LU orcid ; Rich, R. M. ; Schultheis, M. ; Renaud, F. LU ; Spitoni, E. ; Fritz, T. K. ; Mastrobuono-Battisti, A. LU ; Origlia, L. and Matteucci, F. , et al. (2020) In Astrophysical Journal 894(1).
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... (More)

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.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Astrophysical Journal
volume
894
issue
1
article number
26
publisher
American Astronomical Society
external identifiers
  • scopus:85088388608
ISSN
0004-637X
DOI
10.3847/1538-4357/ab8226
language
English
LU publication?
yes
id
7f5ef7fa-27a3-4e59-bdcc-aae79f0c7e6e
date added to LUP
2020-08-05 09:39:20
date last changed
2025-10-14 10:02:04
@article{7f5ef7fa-27a3-4e59-bdcc-aae79f0c7e6e,
  abstract     = {{<p>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.</p>}},
  author       = {{Thorsbro, B. and Ryde, N. and Rich, R. M. and Schultheis, M. and Renaud, F. and Spitoni, E. and Fritz, T. K. and Mastrobuono-Battisti, A. and Origlia, L. and Matteucci, F. and Schödel, R.}},
  issn         = {{0004-637X}},
  language     = {{eng}},
  number       = {{1}},
  publisher    = {{American Astronomical Society}},
  series       = {{Astrophysical Journal}},
  title        = {{Detailed Abundances in the Galactic Center : Evidence of a Metal-rich Alpha-enhanced Stellar Population}},
  url          = {{http://dx.doi.org/10.3847/1538-4357/ab8226}},
  doi          = {{10.3847/1538-4357/ab8226}},
  volume       = {{894}},
  year         = {{2020}},
}