1. Exploring the Galactic Anticenter Substructure with LAMOST and Gaia DR2.
- Author
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Li, Jing, Xue, Xiang-Xiang, Liu, Chao, Zhang, Bo, Rix, Hans-Walter, Carlin, Jeffrey L., Yang, Chengqun, Mendez, Rene A., Zhong, Jing, Tian, Hao, Zhang, Lan, Xu, Yan, Wu, Yaqian, Zhao, Gang, and Chang, Ruixiang
- Subjects
MOMENTUM distributions ,ANGULAR distribution (Nuclear physics) ,DISTRIBUTION of stars ,ANGULAR momentum (Mechanics) ,MOLECULAR clouds ,ACCRETION disks ,PROTOPLANETARY disks - Abstract
We characterize the kinematic and chemical properties of 589 Galactic anticenter substructure stars (GASS) with K/M giants in integrals-of-motion space. These stars likely include members of previously identified substructures such as Monoceros, A13, and the Triangulum-Andromeda cloud. We show that these stars are in nearly circular orbits on both sides of the Galactic plane. We can see a velocity (V
Z ) gradient along Y-axis especially for the south GASS members. Our GASS members have similar energy and angular momentum distributions to thin-disk stars. Their location in [α/M] versus [M/H] space is more metal-poor than typical thin-disk stars, with [α/M] lower than that of the thick disk. We infer that our GASS members are part of the outer metal-poor disk stars and that the outer disk extends to 30 kpc. Considering the distance range and α-abundance features, GASS could be formed after the thick disk was formed due to the molecular cloud density decreasing in the outer disk where the star-formation rate might be less efficient compared to the inner disk. [ABSTRACT FROM AUTHOR]- Published
- 2021
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