Visit Nearby Halo Substructures Using LAMOST DR9 MRS Data

ASTROPHYSICAL JOURNAL(2024)

引用 0|浏览4
暂无评分
摘要
Based on the LAMOST DR9 Medium Resolution Spectra (MRS) catalog, combined with astrometries from Gaia DR3, we conducted an investigation into the substructures in the stellar halo to obtain their chemical and kinematic information. We employed the HDBSCAN algorithm in the (L z , E, L xy ) space for clustering and utilized Mahalanobis distance to merge the clustering results. Ultimately, within the LAMOST DR9 MRS catalog, we identified members of Gaia-Sausage-Enceladus (GSE), Helmi streams, and the high-alpha disk and in situ halo. Additionally, there are three clusters that cannot be correlated with known substructures. Based on their angular momentum (L z ) characteristics, we have tentatively named two of them High-L z -Cluster-1 (HLC-1) and High-L z -Cluster-2 (HLC-2), both exhibiting high angular momentum (L z ) features. The third cluster, owing to its extremely low L z , is termed the Low-L z -Cluster. Then detailed analysis about those substructures are executed including member stars' identification and kinematic and chemical distribution. The resulting GSE member stars exhibit a well-defined metallicity distribution function with its peak at [Fe/H] similar to -1.2, consistent with previous findings, and we found there appear to be some differences in the distribution on the V total-r gal plane between GSE and its included Splash component. Regarding Helmi streams, in the [Mg/Fe]-[Fe/H] plane we detected potential traces of the alpha-knee phenomenon at [Fe/H] similar to -1.53. Finally, we tentatively provide the possible origin for the HLC-1 and HLC-2.
更多
查看译文
关键词
Galaxy kinematics,Galaxy structure,Galaxy stellar halos,Galaxy dynamics
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要