Disentangling the Galactic Halo with APOGEE. I. Chemical and Kinematical Investigation of Distinct Metal-poor Populations
AuthorHayes, Christian R.
Majewski, Steven R.
Prieto, Carlos Allende
Schuster, William J.
Smith, Verne V.
Beers, Timothy C.
Fernández-Trincado, J. G.
García-Hernández, D. A.
Lane, Richard R.
Matthews, Allison M.
Tissera, Patricia B.
AffiliationUniv Arizona, Steward Observ
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PublisherIOP PUBLISHING LTD
CitationDisentangling the Galactic Halo with APOGEE. I. Chemical and Kinematical Investigation of Distinct Metal-poor Populations 2018, 852 (1):49 The Astrophysical Journal
JournalThe Astrophysical Journal
Rights© 2018. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractWe find two chemically distinct populations separated relatively cleanly in the [Fe/H]-[Mg/Fe] plane, but also distinguished in other chemical planes, among metal-poor stars (primarily with metallicities [Fe/H] < -0.9) observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and analyzed for Data Release 13 (DR13) of the Sloan Digital Sky Survey. These two stellar populations show the most significant differences in their [X/Fe] ratios for the alpha-elements, C+N, Al, and Ni. In addition to these populations having differing chemistry, the low metallicity high-Mg population (which we denote "the HMg population") exhibits a significant net Galactic rotation, whereas the low-Mg population (or "the LMg population") has halo-like kinematics with little to no net rotation. Based on its properties, the origin of the LMg population is likely an accreted population of stars. The HMg population shows chemistry (and to an extent kinematics) similar to the thick disk, and is likely associated with in situ formation. The distinction between the LMg and HMg populations mimics the differences between the populations of low-and high-a halo stars found in previous studies, suggesting that these are samples of the same two populations.
VersionFinal published version
SponsorsNational Science Foundation [AST-1312863, AST-1616636]; Spanish MINECO [AYA-2014-56359-P]; PAPIIT of Mxico [IN103014]; CONACyT of Mexico ; PAPIIT of Mexico [IG100115, IA101215, IA101517]; MINECO of Spain [AYA2015-65205-P]; Physics Frontier Center/JINA Center for the Evolution of the Elements (JINA-CEE); US National Science Foundation; Chilean BASAL Centro de Excelencia en Astrofisica y Tecnologias Afines (CATA) grant [PFB-06/2007]; Ramon y Cajal fellowship [RYC-2013-14182]; Spanish Ministry of Economy and Competitiveness (MINECO) [AYA-2014-58082-P]; Chilean Ministry of Economy, Development, and Tourism's Millennium Science Initiative [IC120009]; STFC/Newton Fund [ST/M007995/1]; CONICYT/Newton Fund [DPI20140114]; Alfred P. Sloan Foundation; U.S. Department of Energy Office of Science; Center for High-Performance Computing at the University of Utah; Brazilian Participation Group; Carnegie Institution for Science; Carnegie Mellon University; Chilean Participation Group; French Participation Group; Harvard-Smithsonian Center for Astrophysics; Instituto de Astrofisica de Canarias; Johns Hopkins University; Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo; Lawrence Berkeley National Laboratory; Leibniz Institut fur Astrophysik Potsdam (AIP); Max-Planck-Institut fur Astronomie (MPIA Heidelberg); Max-Planck-Institut fur Astrophysik (MPA Garching); Max-Planck-Institut fur Extraterrestrische Physik (MPE); National Astronomical Observatory of China; New Mexico State University; New York University; University of Notre Dame; Observatario Nacional / MCTI; Ohio State University; Pennsylvania State University; Shanghai Astronomical Observatory; United Kingdom Participation Group; Universidad Nacional Autonoma de Mexico; University of Arizona; University of Colorado Boulder; University of Oxford; University of Portsmouth; University of Utah; University of Virginia; University of Washington; University of Wisconsin; Vanderbilt University; Yale University; [PHY 14-30152]