Selecting accreted populations : Metallicity, elemental abundances, and ages of the Gaia-Sausage-Enceladus and Sequoia populations
(2021) In Monthly Notices of the Royal Astronomical Society 508(1). p.1489-1508- Abstract
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... (More)
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.
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- author
- Feuillet, Diane K. LU ; Sahlholdt, Christian L. LU ; Feltzing, Sofia LU and Casagrande, Luca
- organization
- publishing date
- 2021-11-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Galaxy: abundances, Galaxy: formation, Galaxy: halo, Galaxy: kinematics and dynamics, Galaxy: stellar content
- in
- Monthly Notices of the Royal Astronomical Society
- volume
- 508
- issue
- 1
- pages
- 20 pages
- publisher
- Oxford University Press
- external identifiers
-
- scopus:85118182461
- ISSN
- 0035-8711
- DOI
- 10.1093/mnras/stab2614
- 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
- 07af36cb-26d6-4892-a4c8-58f7fb6dc8c2
- date added to LUP
- 2021-11-13 09:24:15
- date last changed
- 2024-04-20 16:16:13
@article{07af36cb-26d6-4892-a4c8-58f7fb6dc8c2, abstract = {{<p>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.</p>}}, author = {{Feuillet, Diane K. and Sahlholdt, Christian L. and Feltzing, Sofia and Casagrande, Luca}}, issn = {{0035-8711}}, keywords = {{Galaxy: abundances; Galaxy: formation; Galaxy: halo; Galaxy: kinematics and dynamics; Galaxy: stellar content}}, language = {{eng}}, month = {{11}}, number = {{1}}, pages = {{1489--1508}}, publisher = {{Oxford University Press}}, series = {{Monthly Notices of the Royal Astronomical Society}}, title = {{Selecting accreted populations : Metallicity, elemental abundances, and ages of the Gaia-Sausage-Enceladus and Sequoia populations}}, url = {{http://dx.doi.org/10.1093/mnras/stab2614}}, doi = {{10.1093/mnras/stab2614}}, volume = {{508}}, year = {{2021}}, }