A Catalog of Early-type Runaway Stars from LAMOST DR8

Abstract

Runaway stars are OB-type stars ejected from their birthplace with large peculiar velocities. The leading hypothesis addressed in their formation includes the supernova ejection mechanism and the dynamic ejection scenario. Identification of runaway populations is the first step to investigating their formation and evolution. Here we present our work of searching for Galactic runaway candidate stars from the Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) Medium Resolution Survey Data Release 8 (DR8) database. After studying the kinematic properties for a collection of 4432 early-type stars, predominantly B-type stars, using radial velocity measurements from LAMOST DR8 and astrometric solutions made by Gaia Data Release 3, we identified 229 runaway candidate stars. They span a wide distribution in projected rotational velocities. We investigated the Galactic spatial distribution of the runaway population and noticed that most of them likely reside within the Galactic thin disk. Based upon analyzing the Doppler shifts of the candidate stars, we found two binary runaway candidates displaying velocity variations with estimated orbital periods of 40 and 61 days.