Dynamical Star-forming History of Per OB2

Abstract

Abstract We analyze the internal dynamics of young stars toward Perseus using Gaia EDR3 data, including Per OB2 and California Cloud. Interpreting the current dynamics, we speculate that Per OB2 may have formed from two separate clouds that have begun forming stars in close proximity to each other. IC 348 is caught in the middle between the two of them, inheriting kinematics of both, and it stands out as a possible site of cloud–cloud interaction. We also consider the possibility of a past supernova in Per OB2—while one has likely occurred, it does not appear to have caused any obvious triggered star formation, but it has created a shock that has swept the molecular gas away from IC 348. Finally, we examine a recently proposed shell between Taurus and Perseus. While its origin is unknown, we find no support for an expanding bubble in stellar kinematics, nor can we identify a likely progenitor for a supernova that may have caused it, disfavoring this scenario in the formation of this apparent shell.