Sofia Feltzing
Professor
Selecting accreted populations : Metallicity, elemental abundances, and ages of the Gaia-Sausage-Enceladus and Sequoia populations
Författare
Summary, in English
Identifying stars found in the Milky Way as having formed in situ or accreted can be a complex and uncertain undertaking. We use Gaia kinematics and APOGEE elemental abundances to select stars belonging to the Gaia-Sausage-Enceladus (GSE) and Sequoia accretion events. These samples are used to characterize the GSE and Sequoia population metallicity distribution functions, elemental abundance patterns, age distributions, and progenitor masses. We find that the GSE population has a mean [Fe/H] ∼-1.15 and a mean age of 10-12 Gyr. GSE has a single sequence in [Mg/Fe] versus [Fe/H] consistent with the onset of SN Ia Fe contributions and uniformly low [Al/Fe] of ∼-0.25 dex. The derived properties of the Sequoia population are strongly dependent on the kinematic selection. We argue the selection with the least contamination is Jφ/Jtot < -0.6 and (Jz - JR)/Jtot < 0.1. This results in a mean [Fe/H] ∼-1.3 and a mean age of 12-14 Gyr. The Sequoia population has a complex elemental abundance distribution with mainly high-[Mg/Fe] stars. We use the GSE [Al/Fe] versus [Mg/H] abundance distribution to inform a chemically based selection of accreted stars, which is used to remove possible contaminant stars from the GSE and Sequoia samples.
Avdelning/ar
- Astronomi - Har omorganiserats
- eSSENCE: The e-Science Collaboration
Publiceringsår
2021-11-01
Språk
Engelska
Sidor
1489-1508
Publikation/Tidskrift/Serie
Monthly Notices of the Royal Astronomical Society
Volym
508
Issue
1
Dokumenttyp
Artikel i tidskrift
Förlag
Oxford University Press
Ämne
- Astronomy, Astrophysics and Cosmology
Nyckelord
- Galaxy: abundances
- Galaxy: formation
- Galaxy: halo
- Galaxy: kinematics and dynamics
- Galaxy: stellar content
Status
Published
ISBN/ISSN/Övrigt
- ISSN: 0035-8711