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The COMBS Survey - III. The chemodynamical origins of metal-poor bulge stars

Lucey, Madeline ; Hawkins, Keith ; Ness, Melissa ; Nelson, Tyler ; Debattista, Victor P. ; Luna, Alice ; Bensby, Thomas LU orcid ; Freeman, Kenneth C. and Kobayashi, Chiaki (2022) In Monthly Notices of the Royal Astronomical Society 509(1). p.122-144
Abstract

The characteristics of the stellar populations in the Galactic bulge info and constrain the Milky Way's foation and evolution. The metal-poor population is particularly important in light of cosmological silations, which predict that some of the oldest stars in the Galaxy now reside in its centre. The metal-poor bulge appears to consist of ltiple stellar populations that require dynamical analyses to disentangle. In this work, we undertake a detailed chemodynamical study of the metal-poor stars in the inner Galaxy. Using R 20 000 VLT/GIRAFFE spectra of 319 metal-poor (-2.55 dex ≤ [Fe/H] ≤ 0.83 dex, with $overline{ {[Fe/H]}}$ = -0.84 dex) stars, we perfo stellar parameter analysis and report 12 elemental abundances (C, Na, Mg, Al, Si,... (More)

The characteristics of the stellar populations in the Galactic bulge info and constrain the Milky Way's foation and evolution. The metal-poor population is particularly important in light of cosmological silations, which predict that some of the oldest stars in the Galaxy now reside in its centre. The metal-poor bulge appears to consist of ltiple stellar populations that require dynamical analyses to disentangle. In this work, we undertake a detailed chemodynamical study of the metal-poor stars in the inner Galaxy. Using R 20 000 VLT/GIRAFFE spectra of 319 metal-poor (-2.55 dex ≤ [Fe/H] ≤ 0.83 dex, with $overline{ {[Fe/H]}}$ = -0.84 dex) stars, we perfo stellar parameter analysis and report 12 elemental abundances (C, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Zn, Ba, and Ce) with precisions of ≈0.10 dex. Based on kinematic and spatial properties, we categorize the stars into four groups, associated with the following Galactic structures: the inner bulge, the outer bulge, the halo, and the disc. We find evidence that the inner and outer bulge population is more chemically complex (i.e. higher chemical dimensionality and less correlated abundances) than the halo population. This result suggests that the older bulge population was enriched by a larger diversity of nucleosynthetic events. We also find one inner bulge star with a [Ca/Mg] ratio consistent with theoretical pair-instability supernova yields and two stars that have chemistry consistent with globular cluster stars.

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author
; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
abundances, bulge, evolution, Galaxy, Population II, stars
in
Monthly Notices of the Royal Astronomical Society
volume
509
issue
1
pages
23 pages
publisher
Oxford University Press
external identifiers
  • scopus:85121255627
ISSN
0035-8711
DOI
10.1093/mnras/stab2878
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
id
baaffd6c-2a39-427d-8f7b-4c99bf554e06
date added to LUP
2022-01-11 17:50:06
date last changed
2024-05-16 11:09:17
@article{baaffd6c-2a39-427d-8f7b-4c99bf554e06,
  abstract     = {{<p>The characteristics of the stellar populations in the Galactic bulge info and constrain the Milky Way's foation and evolution. The metal-poor population is particularly important in light of cosmological silations, which predict that some of the oldest stars in the Galaxy now reside in its centre. The metal-poor bulge appears to consist of ltiple stellar populations that require dynamical analyses to disentangle. In this work, we undertake a detailed chemodynamical study of the metal-poor stars in the inner Galaxy. Using R 20 000 VLT/GIRAFFE spectra of 319 metal-poor (-2.55 dex ≤ [Fe/H] ≤ 0.83 dex, with $overline{ {[Fe/H]}}$ = -0.84 dex) stars, we perfo stellar parameter analysis and report 12 elemental abundances (C, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Zn, Ba, and Ce) with precisions of ≈0.10 dex. Based on kinematic and spatial properties, we categorize the stars into four groups, associated with the following Galactic structures: the inner bulge, the outer bulge, the halo, and the disc. We find evidence that the inner and outer bulge population is more chemically complex (i.e. higher chemical dimensionality and less correlated abundances) than the halo population. This result suggests that the older bulge population was enriched by a larger diversity of nucleosynthetic events. We also find one inner bulge star with a [Ca/Mg] ratio consistent with theoretical pair-instability supernova yields and two stars that have chemistry consistent with globular cluster stars. </p>}},
  author       = {{Lucey, Madeline and Hawkins, Keith and Ness, Melissa and Nelson, Tyler and Debattista, Victor P. and Luna, Alice and Bensby, Thomas and Freeman, Kenneth C. and Kobayashi, Chiaki}},
  issn         = {{0035-8711}},
  keywords     = {{abundances; bulge; evolution; Galaxy; Population II; stars}},
  language     = {{eng}},
  month        = {{01}},
  number       = {{1}},
  pages        = {{122--144}},
  publisher    = {{Oxford University Press}},
  series       = {{Monthly Notices of the Royal Astronomical Society}},
  title        = {{The COMBS Survey - III. The chemodynamical origins of metal-poor bulge stars}},
  url          = {{http://dx.doi.org/10.1093/mnras/stab2878}},
  doi          = {{10.1093/mnras/stab2878}},
  volume       = {{509}},
  year         = {{2022}},
}