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

Madeline Lucey, Keith Hawkins, Melissa Ness, Tyler Nelson, Victor P. Debattista, Alice Luna, Thomas Bensby, Kenneth C. Freeman, Chiaki Kobayashi

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskriftPeer review


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.

Sidor (från-till)122-144
Antal sidor23
TidskriftMonthly Notices of the Royal Astronomical Society
StatusPublished - 2022 jan. 1

Bibliografisk information

Publisher Copyright:
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.

Ämnesklassifikation (UKÄ)

  • Astronomi, astrofysik och kosmologi


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