Dynamical star forming history of Per OB2

TL;DR

This study investigates the internal dynamics and star formation history of Per OB2 using Gaia data, suggesting a complex formation involving multiple clouds, a past supernova, and challenging the shell hypothesis.

Contribution

It provides new insights into the formation and dynamical interactions of stars in Per OB2, including the role of cloud interactions and supernova events.

Findings

Per OB2 likely formed from two separate clouds.

IC 348 exhibits mixed kinematics from both clouds.

No evidence supports an expanding shell or supernova origin for the observed shell.

Abstract

We analyze the internal dynamics of young stars towards 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 a close proximity of 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 a possibility of a past supernova in Per OB2 - while one had likely occurred, it did not appear to have caused any obvious triggered star formation, but it has created a shock which has swept away 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.