GaiaDR3 Galactic runaway O, Be stars

We found 69 Be runaway stars, 47 of which were not previously identified as runaways. The dispersion of runaway stars is a few times higher in Z and b than that of field stars. This is explained by the ejections they underwent when they became runaways.

The percentage of runaways is 25.4% for O-type stars, and it is 5.2% for Be-type stars. In addition, we conducted simulations in three dimensions for our catalogs. They revealed that these percentages could increase to ~30% and ~6.7%, respectively.

Our runaway stars include seven X-ray binaries and one gamma-ray binary. Moreover, we obtain velocity dispersions of ~5km/s perpendicular to the Galactic plane for O- and Be-type field stars. These values increase in the Galactic plane to ~7km/s for O-type stars due to uncertainties and to ~9km/s for Be-type stars due to Galactic velocity diffusion.

The excellent Gaia DR3 astrometric data have allowed us to identify a significant number of O-type and Be-type runaways in the GOSC and BeSS catalogs. The higher percentages and higher velocities found for O-type compared to Be-type runaways underline that the dynamical ejection scenario is more likely that the binary supernova scenario. Our results open the door to identifying new high-energy systems among our runaways by conducting detailed studies.