Thomas Bensby
Senior lecturer
The COMBS Survey - III. The chemodynamical origins of metal-poor bulge stars
Author
Summary, in English
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.
Department/s
- Lund Observatory - Has been reorganised
Publishing year
2022-01-01
Language
English
Pages
122-144
Publication/Series
Monthly Notices of the Royal Astronomical Society
Volume
509
Issue
1
Document type
Journal article
Publisher
Oxford University Press
Topic
- Astronomy, Astrophysics and Cosmology
Keywords
- abundances
- bulge
- evolution
- Galaxy
- Population II
- stars
Status
Published
ISBN/ISSN/Other
- ISSN: 0035-8711