Existence of the Metal-rich Stellar Halo and High-velocity Thick Disk in the Galaxy

  title={Existence of the Metal-rich Stellar Halo and High-velocity Thick Disk in the Galaxy},
  author={Yepeng Yan and Cuihua Du and Hefan Li and Jian-rong Shi and Jun Ma and Heidi Jo Newberg},
  journal={The Astrophysical Journal},
Based on the second Gaia data release (DR2), combined with the LAMOST and APOGEE spectroscopic surveys, we study the kinematics and metallicity distribution of the high-velocity stars that have a relative speed of at least 220 with respect to the local standard of rest in the Galaxy. The rotational velocity distribution of the high-velocity stars with [Fe/H] dex can be well described by a two-Gaussian model, with peaks at and , associated with the thick disk and halo, respectively. This implies… 

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