The First Hypervelocity Star from the LAMOST Survey

Abstract

We report the first hypervelocity star (HVS) discovered from the LAMOST spectroscopic survey. It is a B-type star with a heliocentric radial velocity about 620 km/s, which projects to a Galactocentric radial velocity component of ~477 km/s. With a heliocentric distance of ~13 kpc and an apparent magnitude of ~13 mag, it is the nearest bright HVS currently known. With a mass of ~9Msun, it is one of the three most massive HVSs discovered so far. The star is clustered on the sky with many other known HVSs, with the position suggesting a possible connection to Galactic center structures. With the current poorly-determined proper motion, a Galactic center origin of this HVS remains consistent with the data at the 1sigma level, while a disk run-away origin cannot be excluded. We discuss the potential of the LAMOST survey to discover a large statistical sample of HVSs of different types.

5 pages, 5 figures, accepted for publication in ApJL, updated contour plot for the ejection positions after correcting a mistake in the calculation

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• Constraining Solar position and velocity with a Nearby Hypervelocity Star
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• Three New Late-type Hypervelocity Star Candidates from Gaia DR2 with Refined Selection Criteria
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• Nearby Low-Mass Hypervelocity Stars