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Existence of the Metal-rich Stellar Halo and High-velocity Thick Disk in the Galaxy
Yan,Yepeng1,2; Du,Cuihua3; Li,Hefan1; Shi,Jianrong3,4; Ma,Jun3,4; Newberg,Heidi Jo5
2020-11-01
Source PublicationThe Astrophysical Journal
ISSN0004-637X
Volume903Issue:2
AbstractAbstract Based on the second Gaia data release (DR2), combined with the LAMOST and APOGEE spectroscopic surveys, we study the kinematics and metallicity distribution of the high-velocity stars that have a relative speed of at least 220 with respect to the local standard of rest in the Galaxy. The rotational velocity distribution of the high-velocity stars with [Fe/H] dex can be well described by a two-Gaussian model, with peaks at and , associated with the thick disk and halo, respectively. This implies that there should exist a high-velocity thick disk (HVTD) and a metal-rich stellar halo (MRSH) in the Galaxy. The HVTD stars have the same position as the halo in the Toomre diagram but show the same rotational velocity and metallicity as the canonical thick disk. The MRSH stars have basically the same rotational velocity, orbital eccentricity, and position in the Lindblad and Toomre diagram as the canonical halo stars, but they are more metal-rich. Furthermore, the metallicity distribution function of our sample stars are well fitted by a four-Gaussian model, associated with the outer halo, inner halo, MRSH, and HVTD, respectively. Chemical and kinematic properties and age imply that the MRSH and HVTD stars may form in situ.
KeywordGalaxy stellar halos Galaxy stellar disks Galaxy structure Galaxy kinematics Galaxy abundances
DOI10.3847/1538-4357/abbd3d
Language英语
WOS IDIOP:0004-637X-903-2-abbd3d
PublisherThe American Astronomical Society
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Document Type期刊论文
Identifierhttp://ir.bao.ac.cn/handle/114a11/62319
Collection中国科学院国家天文台
Corresponding AuthorDu,Cuihua
Affiliation1.School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
2.Department of Astronomy, Beijing Normal University, Beijing 100875, People’s Republic of China
3.College of Astronomy and Space Sciences, University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China; ducuihua@ucas.ac.cn
4.Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, People’s Republic of China
5.Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
Recommended Citation
GB/T 7714
Yan,Yepeng,Du,Cuihua,Li,Hefan,et al. Existence of the Metal-rich Stellar Halo and High-velocity Thick Disk in the Galaxy[J]. The Astrophysical Journal,2020,903(2).
APA Yan,Yepeng,Du,Cuihua,Li,Hefan,Shi,Jianrong,Ma,Jun,&Newberg,Heidi Jo.(2020).Existence of the Metal-rich Stellar Halo and High-velocity Thick Disk in the Galaxy.The Astrophysical Journal,903(2).
MLA Yan,Yepeng,et al."Existence of the Metal-rich Stellar Halo and High-velocity Thick Disk in the Galaxy".The Astrophysical Journal 903.2(2020).
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