An outcast star is zooming out of the Milky Way, the first ever seen escaping the galaxy, astronomers reported on Tuesday.
The star is heading for the emptiness of intergalactic space after being ejected from the heart of the Milky Way following a close encounter with a black hole, said Warren Brown, an astronomer at the Harvard-Smithsonian Center for Astrophysics. The outcast is going so fast — over 1.5 million mph —that astronomers believe it was lobbed out of the galaxy by the tremendous force of a black hole, thought to sit at the Milky Way’s centre.
That speed is about twice the velocity needed to escape the galaxy’s grip, Brown said by telephone.
“We’re tempted to call it the outcast star because it was forcefully tossed from its home,” he said.
The star used to be part of a binary pair, waltzing with its companion star close to the rim of the black hole. As the two stars twirled around each other, they were pulled towards the edge of the black hole, one of those monster drains in space whose gravity swallows anything in its vicinity.
While the companion star was captured by the black hole, the outcast continued on its path. That very speed, coupled with the twirling, sent the outcast zooming toward the edge of the Milky Way.