Identifying Galactic Halo Substructure in 6D Phase Space Using ~13,000 LAMOST K Giants
Yang,Chengqun1,2; Xue,Xiang-Xiang1; Li,Jing3,4; Zhang,Lan1; Liu,Chao1,2; Zhao,Gang1,2; Chang,Jiang1; Tian,Hao1; Li,Chengdong1,2
Source PublicationThe Astrophysical Journal
AbstractAbstract We construct a large halo K-giant sample by combining the positions, distances, radial velocities, and metallicities of over 13,000 LAMOST DR5 halo K giants with the Gaia DR2 proper motions, which covers a Galactocentric distance range of 5–120 kpc. Using a position–velocity clustering estimator (the 6Distance), we statistically quantify the presence of position–velocity substructure at high significance: K giants have more close pairs in position–velocity space than a smooth stellar halo. We find that the amount of substructure in the halo increases with increasing distance and metallicity. With a percolation algorithm named friends-of-friends to identify groups, we identify members belonging to Sagittarius (Sgr) Streams, Monoceros Ring, Virgo Overdensity, Hercules–Aquila Cloud, Orphan Streams, and other unknown substructures and find that the Sgr streams account for a large part of grouped stars beyond 20 kpc and enhance the increase of substructure with distance and metallicity. For the first time, we identify spectroscopic members of Monoceros Ring in the southern and northern Galactic hemispheres, which presents a rotation of about 185 km s?1 and a mean metallicity of ?0.66 dex.
KeywordGalaxy: evolution Galaxy: formation Galaxy: halo Galaxy: kinematics and dynamics
WOS IDIOP:0004-637X-880-1-ab2462
PublisherThe American Astronomical Society
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Document Type期刊论文
Affiliation1.National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100101, People’s Republic of China,
2.School of Astronomy and Space Science, University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, People’s Republic of China
3.Physics and Space Science College, China West Normal University, 1 ShiDa Road, Nanchong 637002, People’s Republic of China
4.SHAO, Chinese Academy of Sciences, Nandan Road, Shanghai 200030, People’s Republic of China
First Author AffilicationNational Astronomical Observatories, Chinese Academy of Sciences
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GB/T 7714
Yang,Chengqun,Xue,Xiang-Xiang,Li,Jing,等. Identifying Galactic Halo Substructure in 6D Phase Space Using ~13,000 LAMOST K Giants[J]. The Astrophysical Journal,2019,880(1).
APA Yang,Chengqun.,Xue,Xiang-Xiang.,Li,Jing.,Zhang,Lan.,Liu,Chao.,...&Li,Chengdong.(2019).Identifying Galactic Halo Substructure in 6D Phase Space Using ~13,000 LAMOST K Giants.The Astrophysical Journal,880(1).
MLA Yang,Chengqun,et al."Identifying Galactic Halo Substructure in 6D Phase Space Using ~13,000 LAMOST K Giants".The Astrophysical Journal 880.1(2019).
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