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Abundances of disk and bulge giants from high-resolution optical spectra : II. O, Mg, Co, and Ti in the bulge sample

Jönsson, H. LU ; Ryde, N. LU ; Schultheis, M. and Zoccali, M. (2017) In Astronomy and Astrophysics 598.
Abstract

Context. Determining elemental abundances of bulge stars can, via chemical evolution modeling, help to understand the formation and evolution of the bulge. Recently there have been claims both for and against the bulge having a different [α/Fe] versus [Fe/H] trend as compared to the local thick disk. This could possibly indicate a faster, or at least different, formation timescale of the bulge as compared to the local thick disk. Aims. We aim to determine the abundances of oxygen, magnesium, calcium, and titanium in a sample of 46 bulge K giants, 35 of which have been analyzed for oxygen and magnesium in previous works, and compare this sample to homogeneously determined elemental abundances of a local disk sample of 291 K giants.... (More)

Context. Determining elemental abundances of bulge stars can, via chemical evolution modeling, help to understand the formation and evolution of the bulge. Recently there have been claims both for and against the bulge having a different [α/Fe] versus [Fe/H] trend as compared to the local thick disk. This could possibly indicate a faster, or at least different, formation timescale of the bulge as compared to the local thick disk. Aims. We aim to determine the abundances of oxygen, magnesium, calcium, and titanium in a sample of 46 bulge K giants, 35 of which have been analyzed for oxygen and magnesium in previous works, and compare this sample to homogeneously determined elemental abundances of a local disk sample of 291 K giants. Methods. We used spectral synthesis to determine both the stellar parameters and elemental abundances of the bulge stars analyzed here. We used the exact same method that we used to analyze the comparison sample of 291 local K giants in Paper I of this series. Results. Compared to the previous analysis of the 35 stars in our sample, we find lower [Mg/Fe] for [Fe/H] >-0.5, and therefore contradict the conclusion about a declining [O/Mg] for increasing [Fe/H]. We instead see a constant [O/Mg] over all the observed [Fe/H] in the bulge. Furthermore, we find no evidence for a different behavior of the alpha-iron trends in the bulge as compared to the local thick disk from our two samples.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Galaxy: bulge, Galaxy: evolution, Stars: abundances
in
Astronomy and Astrophysics
volume
598
publisher
EDP Sciences
external identifiers
  • scopus:85012055044
  • wos:000394465000100
ISSN
0004-6361
DOI
10.1051/0004-6361/201629129
language
English
LU publication?
yes
id
96f162bc-aa4b-4045-8df7-55ae113afb95
date added to LUP
2017-02-23 10:13:21
date last changed
2018-01-07 11:52:10
@article{96f162bc-aa4b-4045-8df7-55ae113afb95,
  abstract     = {<p>Context. Determining elemental abundances of bulge stars can, via chemical evolution modeling, help to understand the formation and evolution of the bulge. Recently there have been claims both for and against the bulge having a different [α/Fe] versus [Fe/H] trend as compared to the local thick disk. This could possibly indicate a faster, or at least different, formation timescale of the bulge as compared to the local thick disk. Aims. We aim to determine the abundances of oxygen, magnesium, calcium, and titanium in a sample of 46 bulge K giants, 35 of which have been analyzed for oxygen and magnesium in previous works, and compare this sample to homogeneously determined elemental abundances of a local disk sample of 291 K giants. Methods. We used spectral synthesis to determine both the stellar parameters and elemental abundances of the bulge stars analyzed here. We used the exact same method that we used to analyze the comparison sample of 291 local K giants in Paper I of this series. Results. Compared to the previous analysis of the 35 stars in our sample, we find lower [Mg/Fe] for [Fe/H] &gt;-0.5, and therefore contradict the conclusion about a declining [O/Mg] for increasing [Fe/H]. We instead see a constant [O/Mg] over all the observed [Fe/H] in the bulge. Furthermore, we find no evidence for a different behavior of the alpha-iron trends in the bulge as compared to the local thick disk from our two samples.</p>},
  articleno    = {A101},
  author       = {Jönsson, H. and Ryde, N. and Schultheis, M. and Zoccali, M.},
  issn         = {0004-6361},
  keyword      = {Galaxy: bulge,Galaxy: evolution,Stars: abundances},
  language     = {eng},
  month        = {02},
  publisher    = {EDP Sciences},
  series       = {Astronomy and Astrophysics},
  title        = {Abundances of disk and bulge giants from high-resolution optical spectra : II. O, Mg, Co, and Ti in the bulge sample},
  url          = {http://dx.doi.org/10.1051/0004-6361/201629129},
  volume       = {598},
  year         = {2017},
}