Double trouble: Gaia reveals (proto)-planetary systems that may experience more than one dense star-forming environment

TL;DR

This paper uses Gaia data to identify young star systems ejected from star-forming regions that may encounter multiple dense environments, affecting their planetary system survival.

Contribution

It demonstrates that star-disc systems can be ejected from one dense region and potentially encounter a second, increasing risks to planetary system stability.

Findings

Identified runaway stars with discs in Gaia DR2 data near Orion Nebula Cluster.

Showed that ejected star systems can encounter multiple dense star-forming regions.

Highlighted increased risks to planetary systems from multiple environmental interactions.

Abstract

Planetary systems appear to form contemporaneously around young stars within young star-forming regions. Within these environments, the chances of survival, as well as the long-term evolution of these systems, are influenced by factors such as dynamical interactions with other stars and photoevaporation from massive stars. These interactions can also cause young stars to be ejected from their birth regions and become runaways. We present examples of such runaway stars in the vicinity of the Orion Nebula Cluster (ONC) found in Gaia DR2 data that have retained their discs during the ejection process. Once set on their path, these runaways usually do not encounter any other dense regions that could endanger the survival of their discs or young planetary systems. However, we show that it is possible for star-disc systems, presumably ejected from one dense star-forming region, to encounter a second dense region, in our case the ONC. While the interactions of the ejected star-disc systems in the second region are unlikely to be the same as in their birth region, a second encounter will increase the risk to the disc or planetary system from malign external effects.