Multiple kinematical populations in Vela OB2 from Gaia DR1 data

Abstract

Context. Recent results using radial-velocity measurements from the Gaia-ESO Survey have led to the discovery of multiple kinematic populations across the Vela OB2 association. We present here a proper-motion study of the same region. <BR /> Aims: Our aim is to test whether or not the radial-velocity populations have a counterpart in proper-motion space, and if so, how the two sets of kinematical data complement each other. <BR /> Methods: This work is based on parallaxes and proper motions from the TGAS catalogue, as part of Gaia DR1. <BR /> Results: Two distinct proper-motion populations are found dispersed across 5 degrees (or 30 pc at their likely distances). Their detailed correspondence to the radial-velocity populations could not be tested because of the paucity of common objects. However, compelling indications are found that one of the new proper-motion populations consists mostly of members of the young cluster NGC 2547, and the other is related to the γ<SUP>2</SUP> Vel cluster. Constraints on the age of the two populations, both of which appear to be only 10-35 Myr old, and their possible mutual interactions within the last 1.5 Myr are discussed.