The origin of high velocity stars from Gaia and LAMOST

Abstract

Based on the second Gaia data (Gaia DR2) and spectroscopy from the LAMOST Data Release 5, we defined the high-velocity (HiVel) stars sample as those stars with $v_{\mathrm{gc}}>0.85v_{\mathrm{esc}}$, and derived the final sample of 24 HiVel stars with stellar astrometric parameters and radial velocities. Most of the HiVel stars are metal-poor and $\alpha$-enhanced. In order to further explore the origin of these HiVel stars, we traced the backwards orbits of each HiVel star in the Galactic potential to derive probability parameters which are used to classify these HiVel stars. Of these, 5 stars are from the tidal debris of disrupted dwarf galaxy and 19 stars are runaway-star candidates which originate from the stellar disk.

6 pages, 5 figures, accepted for publication in ApJL

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Cited by in corpus (9)

• 591 high velocity stars in the Galactic halo selected from LAMOST DR7 and Gaia DR2
• Gaia EDR3 in 6D: Searching for unbound stars in the Galaxy
• New nearby hypervelocity stars and their spatial distribution from Gaia DR2
• Milky Way archaeology using RR Lyrae and type II Cepheids II. High velocity RR Lyrae stars, and mass of the Milky Way
• On the origins of extreme velocity stars as revealed by large-scale Galactic surveys
• 60 candidate high-velocity stars originating from the Sagittarius dwarf spheroidal galaxy in Gaia EDR3
• Flying far and fast: the distribution of distant hypervelocity star candidates from Gaia DR2 data
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• Searching for new Hypervelocity Stars with Gaia DR3 and VLT/FORS2 Spectroscopy