Astronomers have carried out the most…

Astronomers have carried out the most extensive observational study so far of massive runaway stars in the Milky Way, combining detailed measurements of how fast these stars move, how rapidly they spin, and whether they live alone or in binary systems. Researchers from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and the Institute of Space Studies of Catalonia (IEEC), working with the Institute of Astrophysics of the Canary Islands (IAC), focused on a large sample of O-type stars, the most massive and luminous stellar objects in our galaxy.

The study analyzed 214 O-type stars, building the largest sample of galactic O-type runaway stars with combined information on rotation and binarity. The researchers derived the stars' space velocities from Gaia data and obtained their projected rotational velocities and binarity status from the spectroscopic observations. By bringing these measurements together, they were able to link different runaway properties to specific formation pathways.

The results show that most runaway stars rotate slowly, indicating that high space velocity does not necessarily go hand in hand with rapid rotation. However, the subset of runaway stars that do rotate more quickly is more likely to be associated with the supernova scenario, in which a star is spun up and then kicked when its binary companion explodes. This connection suggests that stellar rotation carries a clear imprint of a past binary interaction and supernova event.