Back in 1988, 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 traveling through interstellar space.
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.
Really cool. I find myself thinking about what life would be like on a planet orbiting a star that's zooming around the universe, at 3% the speed of light(!), while constantly under the effects of relativity. I can't help but think it would make a great setting for a novel (or a Doctor Who episode).