Disentangling the Galactic Halo with APOGEE. I. Chemical and Kinematical Investigation of Distinct Metal-poor Populations
Por:
Hayes, Christian R., Majewski, Steven R., Shetrone, Matthew, Fernandez-Alvar, Emma, Allende Prieto, Carlos, Schuster, William J., Carigi, Leticia, Cunha, Katia, Smith, Verne V., Sobeck, Jennifer, Almeida, Andres, Beers, Timothy C., Carrera, Ricardo, Fernandez-Trincado, J. G., Garcia-Hernandez, D. A., Geisler, Doug, Lane, Richard R., Lucatello, Sara, Matthews, Allison M., Minniti, Dante, Nitschelm, Christian, Tang, Baitian, Tissera, Patricia B., Zamora, Olga
Publicada:
1 ene 2018
Resumen:
We 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 α-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-α halo stars found in previous studies, suggesting that these are samples of the same two populations. © 2018. The American Astronomical Society. All rights reserved.
Filiaciones:
Hayes, Christian R.:
Univ Virginia, Dept Astron, Charlottesville, VA 22904 USA
Majewski, Steven R.:
Univ Virginia, Dept Astron, Charlottesville, VA 22904 USA
Shetrone, Matthew:
Univ Texas Austin, McDonald Observ, Ft Davis, TX 79734 USA
Fernandez-Alvar, Emma:
Univ Nacl Autonoma Mexico, Inst Astron, Apartado Postal 70-264, Mexico City 04510, DF, Mexico
Allende Prieto, Carlos:
IAC, Via Lactea, E-38205 Tenerife, Spain
ULL, Dept Astrofis, E-38206 Tenerife, Spain
Schuster, William J.:
Univ Nacl Autonoma Mexico, Inst Astron, AP 106, Ensenada 22800, Baja California, Mexico
Carigi, Leticia:
Univ Nacl Autonoma Mexico, Inst Astron, Apartado Postal 70-264, Mexico City 04510, DF, Mexico
Cunha, Katia:
Observ Nacl, 77 Rua Gen Jose Cristino, BR-20921400 Rio De Janeiro, Brazil
Univ Arizona, Steward Observ, 933 North Cherry Ave, Tucson, AZ 85721 USA
Smith, Verne V.:
Natl Opt Astron Observ, Tucson, AZ 85719 USA
Sobeck, Jennifer:
Univ Washington, Dept Astron, Box 351580, Seattle, WA 98195 USA
Almeida, Andres:
Univ La Serena, Inst Invest Multidisciplinario Ciencia & Tecnol, Benavente 980, La Serena, Chile
Beers, Timothy C.:
Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 USA
Univ Notre Dame, JINA Ctr Evolut Elements, Notre Dame, IN 46556 USA
Carrera, Ricardo:
IAC, Via Lactea, E-38205 Tenerife, Spain
Fernandez-Trincado, J. G.:
Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion, Chile
Univ Bourgogne Franche Comte, Inst Utinam, CNRS, OSU THETA,Observ Besancon,UMR6213, BP 1615, F-25010 Besancon, France
Garcia-Hernandez, D. A.:
IAC, Via Lactea, E-38205 Tenerife, Spain
ULL, Dept Astrofis, E-38206 Tenerife, Spain
Geisler, Doug:
Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion, Chile
Lane, Richard R.:
Millennium Inst Astrophys, Av Vicuna Mackenna 4860, Santiago 7820436, Chile
Pontificia Univ Catolica Chile, Inst Astrofis, Av Vicuna Mackenna 4860, Santiago 7820436, Chile
Lucatello, Sara:
Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy
Matthews, Allison M.:
Univ Virginia, Dept Astron, Charlottesville, VA 22904 USA
Minniti, Dante:
Univ Andres Bello, Dept Ciencias Fis, Fac Ciencias Exactas, Av Fernandez Concha 700, Santiago, Chile
Inst Milenio Astrofis, Av Vicuna Mackenna 4860, Santiago, Chile
Vatican Observ, V00120, Vatican City, Vatican
Nitschelm, Christian:
Univ Antofagasta, Unidad Astron, Ave Angamos 601, Antofagasta 1270300, Chile
Tang, Baitian:
Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion, Chile
Tissera, Patricia B.:
Univ Andres Bello, Dept Ciencias Fis, Fac Ciencias Exactas, Av Fernandez Concha 700, Santiago, Chile
Inst Milenio Astrofis, Av Vicuna Mackenna 4860, Santiago, Chile
Zamora, Olga:
IAC, Via Lactea, E-38205 Tenerife, Spain
ULL, Dept Astrofis, E-38206 Tenerife, Spain
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