Back in , astronomer Jack Hills predicted a type of "rogue"star might exist that is not bound to any particular galaxy. These stars, he reasoned, were periodically ejected from their host galaxy by some sort of mechanism to begin travel. Since that time, astronomers have made numerous discoveries that indicate these rogue, traveling stars indeed do exist, and far from being an occasional phenomenon, they are actually quite common.
And now, in a series of papers that published in arXiv Astrophysics, two Harvard researchers have argued that some of these stars may be traveling close to the speed of light. Known as semi-relativistic hypervelocity stars SHS , these fast-movers are apparently caused by galactic mergers, where the gravitational effect is so strong that it fling stars out of a galaxy entirely.
These stars, the researchers say, may have the potential to spread life throughout the Universe. This finding comes on the heels of two other major announcements. The first occurred in early November when a paper published in the Astrophysical Journal reported that as many as billion rogue stars have been detected in a cluster of galaxies some 4 billion light years away.
This was followed by a study published in Science , where an international team of astronomers claimed that as many as half the stars in the entire universe live outside of galaxies. Credit: ESO. However, the recent observations made by Abraham Loeb and James Guillochon of Harvard University are arguably the most significant yet concerning these rogue celestial bodies.
According to their research papers, these stars may also play a role in spreading life beyond the boundaries of their host galaxies. In their first paper , the researchers trace these stars to galaxy mergers, which presumably lead to the formation of massive black hole binaries in their centers. According to their calculations, these supermassive black holes SMBH will occasionally slingshot stars to semi-relativistic speeds.
