期刊
ASTROPHYSICAL JOURNAL
卷 919, 期 1, 页码 -出版社
IOP Publishing Ltd
DOI: 10.3847/1538-4357/abfa9e
关键词
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资金
- National Key R&D Program of China [2019YFA0405500, 2018YFA0404501]
- National Natural Science Foundation of China [11988101, 11873052, 11890694, 11835057, 11773052, 11761131016, 12025302]
- Chinese Space Station Telescope project
- 111 Project of the Ministry of Education [B20019]
- NSFC [11873034, U1731108, U1731124]
- Hubei Provincial Outstanding Youth Fund [2019CFA087]
- 2018 Heidelberg Summer School for Gaia Data and Science
- Aliyun Fellowship
- Chinese Academy of Sciences President's International Fellowship Initiative Grant [2016PE010, 2021PM0055]
- Postdoctoral Scholar's Fellowship of LAMOST
- Beckwith Trust
- National Development and Reform Commission
- Alfred P. Sloan Foundation
- National Science Foundation
- U.S. Department of Energy Office of Science
- University of Arizona
- Brazilian Participation Group
- Brookhaven National Laboratory
- University of Cambridge
- Carnegie Mellon University
- University of Florida
- French Participation Group
- German Participation Group
- Harvard University
- Instituto de Astrofisica de Canarias
- Michigan State/Notre Dame/JINA Participation Group
- Johns Hopkins University
- Lawrence Berkeley National Laboratory
- Max Planck Institute for Astrophysics
- Max Planck Institute for Extraterrestrial Physics
- New Mexico State University
- New York University
- Ohio State University
- Pennsylvania State University
- University of Portsmouth
- Princeton University
- Spanish Participation Group
- University of Tokyo
- University of Utah
- Vanderbilt University
- University of Virginia
- University of Washington
- Yale University
In this study, the anisotropy profile of the Milky Way's smooth, diffuse stellar halo is analyzed using data from SDSS and LAMOST. The results show that the anisotropy is related to the radial nature of star orbits in different metallicity ranges.
We analyze the anisotropy profile of the Milky Way's smooth, diffuse stellar halo using the Sloan Digital Sky Survey (SDSS) SEGUE blue horizontal branch stars and the SDSS/SEGUE and LAMOST K giants. These intrinsically luminous stars allow us to probe the halo to approximately 100 kpc from the Galactic center. Line-of-sight velocities, distances, metallicities, and proper motions are available for all stars via SDSS/SEGUE, LAMOST, and Gaia, and we use these data to construct a full 7D set consisting of positions, space motions, and metallicity. We remove substructure from our samples using integrals of motion based on the method of Xue et al. We find radially dominated kinematic profiles with nearly constant anisotropy within 20 kpc, beyond which the anisotropy profile gently declines but remains radially dominated to the farthest extents of our sample. Independent of star type or substructure removal, the anisotropy depends on metallicity, such that the orbits of the stars become less radial with decreasing metallicity. For -1.7 < [Fe/H] < -1, the smooth, diffuse halo anisotropy profile begins to decline at Galactocentric distances similar to 20 kpc, from beta similar to 0.9 to 0.7 for K giants and from beta similar to 0.8 to 0.1 for blue horizontal branch stars. For [Fe/H] < -1.7, the smooth, diffuse halo anisotropy remains constant along all distances with 0.2 < beta< 0.7 depending on the metallicity range probed, but independent of star type. These samples are ideal for estimating the total Galactic mass as they represent the virialized stellar halo system.
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