Kinematics of OB Associations and the First Data from the Gaia Satellite

Abstract

The first data release from the Gaia mission (Gaia DR1) is used to study kinematics of OB associations. The mean velocity dispersion in 18 OB associations containing at least 10 stars with proper motions from the TGAS catalog is 3.9 km/s. The contribution of binary systems to the velocity dispersions in OB associations is, on average, 1.2 km/s. Expansion of the OB associations Per OB1 and Car OB1 is observed. This paper is based on a presentation made at the conference “Modern Astrometry 2017,” dedicated to the memory of K.V. Kuimov (Sternberg Astronomical Institute, Moscow State University, October 23–25, 2017).