Groundbreaking Study Unravels Secrets of Runaway Stars

Researchers from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and the Institute of Space Studies of Catalonia (IEEC), in collaboration with the Institute of Astrophysics of the Canary Islands (IAC), have conducted the most extensive observational study to date on runaway massive stars. This research includes an analysis of the rotation and binarity of these stars in the Milky Way.

Understanding Runaway Stars

Runaway stars are stars that move at unusually high speeds, deviating from their birth locations.

The mechanism by which massive runaway stars acquire these velocities has been a subject of investigation. Two primary scenarios have been considered: a violent kick from a companion's supernova explosion in a binary system, or gravitational ejection during close encounters within dense, young star clusters. The relative contribution of these scenarios to the presence of massive runaway stars in the Milky Way was not fully understood.

Methodology: Peering into the Cosmos

The team utilized data from the European Space Agency's (ESA) Gaia mission and spectroscopic information from the IACOB project. They analyzed 214 O-type stars, which are the most massive and luminous stellar objects in the galaxy. To understand their origins, measurements of rotation speed and binarity (whether the star is single or part of a binary system) were combined for the largest sample of galactic O-type runaway stars studied so far.

Key Findings: Unmasking Their Origins

The study's results indicate that most runaway stars rotate slowly.

However, those that exhibit faster rotation are more frequently associated with supernova explosions within binary systems.

Stars with the highest space velocities tend to be single, which suggests their ejection from young clusters through gravitational interactions.