Most "runaway stars" that are zipping through space may be fleeing the breakup of cosmic threesomes, scientists say.
Most of the stars in our galaxy move relatively slowly. However, approximately 20 percent of all massive stars in the Milky Way travel unusually quickly, at more than 67,000 mph (108,000 kph).
The origin of these runaway stars has puzzled astronomers for nearly 50 years. Some suspect they were once partners of stars that exploded as supernovas. Others speculate they were slung through space by the pull of other stars' gravity.
But now, researchers find that most runaway stars may arise from ménages à trois – encounters with binary systems, or paired stars, within the centers of clusters of stars. The runaways get slung outward after strong gravitational interactions with the binaries.
One consequence of these findings is that star clusters may "be born with densities far higher than observed in today's clusters," said study co-author Simon Portegies Zwart, a computational astrophysicist at the University in Leiden in the Netherlands.
"One can learn possibly more about the history of a star cluster by looking away from it," Portegies Zwart told SPACE.com.
