The First Hypervelocity Star from the LAMOST Survey

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.