Anisotropy of the Milky Way's Stellar Halo Using K Giants from LAMOST and Gaia
文献类型：期刊论文
| 作者 | Bird, Sarah A.1,2; Xue, Xiang-Xiang2,3; Liu, Chao2,3; Shen, Juntai1,3,4; Flyn, Chris5; Yang, Chengqun2,3 |
| 刊名 | ASTRONOMICAL JOURNAL
 |
| 出版日期 | 2019-03-01 |
| 卷号 | 157期号:3页码:10 |
| ISSN号 | 0004-6256 |
| 关键词 | galaxies: individual (Milky Way) Galaxy: halo Galaxy: kinematics and dynamics Galaxy: stellar content stars: individual (K giants) stars: kinematics and dynamics |
| DOI | 10.3847/1538-3881/aafd2e |
| 英文摘要 | The anisotropy parameter beta 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 beta 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 (sigma(r), sigma(theta), sigma(phi)) (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 beta approximate to 0.9 for -1.8 <= [Fe/H]< -1.3 (for the bulk of the stars) to beta approximate to 0.6 for the lowest metallicities ([Fe/H]< -1.8). Considering our sample as a whole, beta approximate to 0.8 and beyond 25 kpc, the orbits gradually become less radial and anisotropy decreases to beta < 0.3 past 100 kpc. Within 8 kpc, beta < 0.8. The measurement of anisotropy is affected by substructure and streams, particularly beyond a Galactocentric distance of approximately 25 kpc, where the Sagittarius stream is prominent in the data. These results are complimentary to recent analysis of simulations by Loebman et al. and of SDSS/Gaia DR1 data by Belokurov et al. |
| 资助项目 | Postdoctoral Scholar's Fellowship of LAMOST ; Chinese Academy of Sciences President's International Fellowship Initiative Grant[2016PE010] ; Aliyun Fellowship ; National Key R&D Program of China[2018YFA0404501] ; National Natural Science Foundation of China[11773052] ; National Natural Science Foundation of China[11333003] ; National Natural Science Foundation of China[11761131016] ; China-Chile joint grant from CASSACA ; Newton Advanced Fellowship - Royal Society ; Newton Fund ; Recruitment Program of Global Youth Experts of China ; NSFC[11333003] ; NSFC[11390371] ; NSFC[11873052] ; NSFC[11890694] ; Beckwith Trust ; National Key Basic Research Program of China[2014CB845700] ; National Development and Reform Commission |
| WOS研究方向 | Astronomy & Astrophysics |
| 语种 | 英语 |
| 出版者 | IOP PUBLISHING LTD |
| WOS记录号 | WOS:000460804600003 |
| 源URL | [http://119.78.226.72/handle/331011/31907]  |
| 专题 | 中国科学院上海天文台 |
| 通讯作者 | Bird, Sarah A. |
| 作者单位 | 1.Shanghai Astron Observ, 80 Nandan Rd, Shanghai 200030, Peoples R China 2.Chinese Acad Sci, Natl Astron Observ, Key Lab Opt Astron, 20A Datun Rd, Beijing 100012, Peoples R China 3.Univ Chinese Acad Sci, Sch Astron & Space Sci, 19A Yuquan Rd, Beijing 100049, Peoples R China 4.Shanghai Jiao Tong Univ, Sch Phys & Astron, Dept Astron, Shanghai 200240, Peoples R China 5.Swinburne Univ Technol, Ctr Astrophys & Supercomp, POB 218, Hawth, Australia |
| 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]. ASTRONOMICAL JOURNAL,2019,157(3):10. |
| APA | Bird, Sarah A.,Xue, Xiang-Xiang,Liu, Chao,Shen, Juntai,Flyn, Chris,&Yang, Chengqun.(2019).Anisotropy of the Milky Way's Stellar Halo Using K Giants from LAMOST and Gaia.ASTRONOMICAL JOURNAL,157(3),10. |
| MLA | Bird, Sarah A.,et al."Anisotropy of the Milky Way's Stellar Halo Using K Giants from LAMOST and Gaia".ASTRONOMICAL JOURNAL 157.3(2019):10. |
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来源：上海天文台
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