Differential Rotation of the Halo Traced by K-giant Stars
文献类型：期刊论文
| 作者 | Tian,Hao1; Liu,Chao1 ; Wang,Yougang4; Xu,Yan3; Yang,Chengqun3; Zhang,Bo2; Xue,Xiang-Xiang3
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| 刊名 | The Astrophysical Journal
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| 出版日期 | 2020-08-01 |
| 卷号 | 899期号:2 |
| 关键词 | Milky Way stellar halo Milky Way Galaxy Milky Way rotation Milky Way evolution K giant stars Milky Way dynamics Milky Way disk |
| ISSN号 | 0004-637X |
| DOI | 10.3847/1538-4357/aba1ec |
| 英文摘要 | Abstract We use K-giant stars selected from the LAMOST DR5 to study the variation of the rotational velocity of the Galactic halo at different space positions. Modeling the rotational velocity distribution with both the halo and disk components, we find that the rotational velocity of the halo population decreases almost linearly with increasing vertical distance to the Galactic disk plane, Z, at fixed galactocentric radius, R. The samples are separated into two parts with and . We derive that the decreasing rates along Z for the two subsamples are ?3.07?±?0.63 and ?1.89?±?0.37 km s?1 kpc?1, respectively. Comparing with the TNG simulations, we suggest that this trend is caused by the interaction between the disk and halo. The results from the simulations show that only an oblate halo can provide a decreasing rotational velocity with increasing Z. This indicates that the Galactic halo is oblate with galactocentric radius . On the other hand, the flaring of the disk component (mainly the thick disk) is clearly traced by this study; with R between 12 and 20 kpc, the disk can vertically extend to above the disk plane. What is more interesting is that we find the Gaia–Enceladus–Sausage component has a significant contribution only in the halo with , i.e., a fraction of 23%–47%, while in the outer subsample, the contribution is too low to be well constrained. |
| 语种 | 英语 |
| WOS记录号 | IOP:0004-637X-899-2-ABA1EC |
| 出版者 | The American Astronomical Society |
| 源URL | [http://ir.bao.ac.cn/handle/114a11/61763]  |
| 专题 | 中国科学院国家天文台 |
| 作者单位 | 1.Key Laboratory of Space Astronomy and Technology, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China; liuchao@nao.cas.cn 2.Department of Astronomy, Beijing Normal University, Beijing 100875, People’s Republic of China 3.CAS, Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China 4.Key Laboratory of Computational Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China |
| 推荐引用方式 GB/T 7714 | Tian,Hao,Liu,Chao,Wang,Yougang,et al. Differential Rotation of the Halo Traced by K-giant Stars[J]. The Astrophysical Journal,2020,899(2). |
| APA | Tian,Hao.,Liu,Chao.,Wang,Yougang.,Xu,Yan.,Yang,Chengqun.,...&Xue,Xiang-Xiang.(2020).Differential Rotation of the Halo Traced by K-giant Stars.The Astrophysical Journal,899(2). |
| MLA | Tian,Hao,et al."Differential Rotation of the Halo Traced by K-giant Stars".The Astrophysical Journal 899.2(2020). |
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来源：国家天文台
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