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 of about 620 km s-1, which projects to a Galactocentric radial velocity component of ∼477 km s-1. With a heliocentric distance of ∼13 kpc and an apparent magnitude of ∼13 mag, it is the closest bright HVS currently known. With a mass of ∼9 M ⊙, it is one of the three most massive HVSs discovered so far. The star is clustered on the sky with many other known HVSs, and its position suggests 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 1σ level, while a disk runaway origin cannot be excluded. We discuss the potential of the LAMOST survey to discover a large statistical sample of HVSs of different types. © 2014. The American Astronomical Society. All rights reserved.