The substructures in the local stellar halo from Gaia and LAMOST

Abstract

Based on the second Gaia data release (Gaia DR2) and spectroscopy from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Data, we identified 20,089 halo stars kinematically and chemically. The halo streams in the solar neighborhood could be detected in the space of energy and angular momentum. We reshuffle the velocities of these stars to determine the significance of substructure. Finally, we identify 4 statistically significant substructures that are labeled GL-1 through 4. Among these substructures, GL-1 is previously known stream ("N2" stream) and the rest 3 substructures are new. These substructures may be the debris of dwarf galaxies accretion event, their dynamical and chemical information can help to understand the history of the Milky Way.

12 pages, 9 figures, Accepted for publication in ApJ

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• The R-Process Alliance: Chemo-Dynamically Tagged Groups II. An Extended Sample of Halo $r$-Process-Enhanced Stars
• Dynamically Tagged Groups of Metal-Poor Stars II. The Radial Velocity Experiment Data Release 6
• Finding $r$-II sibling stars in the Milky Way with the Greedy Optimistic Clustering algorithm
• On the Origin of Metal-poor Stars in the Solar Neighborhood
• Existence of the Metal-Rich Stellar Halo and High-velocity Thick Disk in the Galaxy
• Combining Astrometry and Elemental Abundances: The Case of the Candidate Pre-Gaia Halo Moving Groups G03-37, G18-39, and G21-22
• Tomography of stellar halos: what does anisotropy in a stellar halo tell us?
• One Stream or Two -- Exploring Andromeda's North West Stream