August 13, 2015: What happens when you find something in the wrong place at the wrong time? That's a question astronomers have been trying to answer after finding several exploding stars outside the cozy confines of galaxies, where most stars reside. These wayward supernovae also have puzzled astronomers because they exploded billions of years before their predicted detonations. Astronomers using archived observations from several telescopes, including the Hubble Space Telescope, have developed a theory for where these doomed stars come from and how they arrived at their current homes.
According to their scenario, the supernovae were once stars in double-star systems that wandered too close to twin supermassive black holes at the core of a merging galaxy. The black-hole duo gravitationally catapulted the stars out of their home galaxies. The interaction pulled the stars closer together, which accelerated the merger between each pair. Eventually, the stars moved close enough to trigger a supernova blast.See the rest: