Multidimensional Bayesian membership analysis of the Sco OB2 moving group

Abstract

We present a new high-mass membership of the nearby Sco OB2 association based on Hipparcos positions, proper motions and parallaxes, and radial velocities taken from the 2nd Catalogue of Radial Velocities with Astrometric Data (CRVAD-2). The Bayesian membership selection method developed makes no distinction between subgroups of Sco OB2 and utilizes linear models in calculation of membership probabilities. We select 436 members, 88 of which are new members not included in previous membership selections. We include the classical non-members α-Cru and β-Cru as new members as well as the pre-main-sequence stars HIP 79080 and 79081. We also show that the association is well mixed over distances of 8° on the sky, and hence no determination can be made as to the formation process of the entire association.