Kinematics of the young stellar objects associated with the cometary globules in the Gum Nebula

Abstract

An analysis of the proper motion measurements of the young stellar objects (YSOs) associated with the cometary globules (CGs) in the Gum Nebula is presented. While earlier studies based on the radial-velocity measurements of the CGs suggested expansion of the system of the CGs, the observed proper motion of the YSOs shows no evidence for expansion. In particular, the kinematics of two YSOs embedded in CGs are inconsistent with the supernova explosion of the companion of ζ Pup, about 1.5 Myr ago being the cause of the expansion of the system of the CGs. YSOs associated with the CGs share the average proper motion of the member stars of the Vela OB2 association. A few YSOs that have relatively large proper motions are found to show relatively low infrared excesses.