Disentangling the Galactic Halo with APOGEE: II. Chemical and Star Formation Histories for the Two Distinct Populations

The formation processes that led to the current Galactic stellar halo are still under debate. Previous studies have provided evidence for different stellar populations in terms of elemental abundances and kinematics, pointing to different chemical and star-formation histories. In the present work we...

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Bibliographic Details
Published in:arXiv.org 2017-11
Main Authors: Fernández-Alvar, Emma, Carigi, Leticia, Schuster, William J, Hayes, Christian R, Ávila-Vergara, Nancy, Majewski, Steve R, Carlos Allende Prieto, Beers, Timothy C, Sánchez, Sebastián F, Zamora, Olga, García-Hernández, Domingo Aníbla, Tang, Baitian, Fernández-Trincado, José G, Tissera, Patricia, Geisler, Douglas, Villanova, Sandro
Format: Article
Language:English
Subjects:
Calcium
Galactic evolution
Galactic halos
Initial mass function
Kinematics
Magnesium
Metallicity
Organic chemistry
Star & galaxy formation
Star formation
Stellar evolution
Stellar populations
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Summary:The formation processes that led to the current Galactic stellar halo are still under debate. Previous studies have provided evidence for different stellar populations in terms of elemental abundances and kinematics, pointing to different chemical and star-formation histories. In the present work we explore, over a broader range in metallicity (-2.2 < [Fe/H] < -0.5), the two stellar populations detected in the first paper of this series from metal-poor stars in DR13 of the Apache Point Observatory Galactic Evolution Experiment (APOGEE). We aim to infer signatures of the initial mass function (IMF) and the most APOGEE-reliable alpha-elements (O, Mg, Si and Ca). Using simple chemical-evolution models, for each population. Compared with the low-alpha population, we obtain a more intense and longer-lived SFH, and a top-heavier IMF for the high-alpha population.
ISSN:2331-8422
DOI:10.48550/arxiv.1711.06225