Anisotropy of the Milky Way’s Stellar Halo Using K Giants from LAMOST and Gaia

doi:10.3847/1538-3881/aafd2e

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	Anisotropy of the Milky Way’s Stellar Halo Using K Giants from LAMOST and Gaia
	Bird,Sarah A.1,2; Xue,Xiang-Xiang 1,3; Liu,Chao 1,3; Shen,Juntai 2,3,4; Flynn,Chris 5; Yang,Chengqun 1,3
刊名	The Astronomical Journal
	2019-02-08
卷号	157 期号:3
关键词	galaxies: individual (Milky Way) Galaxy: halo Galaxy: kinematics and dynamics Galaxy: stellar content stars: individual (K giants) stars: kinematics and dynamics
ISSN号	0004-6256
DOI	10.3847/1538-3881/aafd2e
英文摘要	Abstract The anisotropy parameter β characterizes the extent to which orbits in stellar systems are predominantly radial or tangential and is likely to constrain, for the stellar halo of the Milky Way, scenarios for its formation and evolution. We have measured β as a function of Galactocentric radius from 5 to 100 kpc for 7664 metal-poor ([Fe/H]?< ?1.3) halo K giants from the LAMOST catalog with line-of-sight velocities and distances, matched to proper motions from the second Gaia data release. We construct full 6D positions and velocities for the K giants to directly measure the three components of the velocity dispersion (σr, σθ, σ?) (in spherical coordinates). We find that the orbits in the halo are radial over our full Galactocentric distance range reaching over 100 kpc. The anisotropy remains remarkably unchanged with Galactocentric radius from approximately 5–25 kpc, with an amplitude that depends on the metallicity of the stars, dropping from β?≈?0.9 for ?1.8?≤?[Fe/H]?
语种	英语
出版者	The American Astronomical Society
WOS记录号	IOP:0004-6256-157-3-AAFD2E
内容类型	期刊论文
源URL	[http://119.78.226.72/handle/331011/31929]
专题	中国科学院上海天文台
作者单位	1.Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Beijing 100012, People's Republic of China; xuexx@nao.cas.cn, liuchao@nao.cas.cn 2.Shanghai Astronomical Observatory, 80 Nandan Road, Shanghai 200030, People's Republic of China; sarahbird@nao.cas.cn, jshen@shao.ac.cn 3.School of Astronomy and Space Science, University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, People’s Republic of China 4.Department of Astronomy, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China 5.Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawth
推荐引用方式 GB/T 7714	Bird,Sarah A.,Xue,Xiang-Xiang,Liu,Chao,et al. Anisotropy of the Milky Way’s Stellar Halo Using K Giants from LAMOST and Gaia[J]. The Astronomical Journal,2019,157(3).
APA	Bird,Sarah A.,Xue,Xiang-Xiang,Liu,Chao,Shen,Juntai,Flynn,Chris,&Yang,Chengqun.(2019).Anisotropy of the Milky Way’s Stellar Halo Using K Giants from LAMOST and Gaia.The Astronomical Journal,157(3).
MLA	Bird,Sarah A.,et al."Anisotropy of the Milky Way’s Stellar Halo Using K Giants from LAMOST and Gaia".The Astronomical Journal 157.3(2019).