Star cluster flung from distant galaxy at 2 million mph
Astronomers have discovered a cluster of several thousand stars that was ejected out of a distant galaxy at a stellar speed of more than two million mph.
The group of “runaway stars,” named HVGC-1 for “hypervelocity globular cluster,” was found by Nelson Caldwell and his team at the Harvard-Smithsonian Center for Astrophysics after they found the bright sphere traveling at a high velocity from the the elliptical galaxy Messier 87.
“Astronomers have found runaway stars before, but this is the first time we’ve found a runaway star cluster,” said Caldwell, also lead author of the resulting study that will be published in “The Astrophysical Journal Letters.”
Since it takes an enormous amount of energy for stars to escape a galaxy, it’s not immediately clear how HVGC-1 broke free from M87. The study suggests that the cluster drifted between the two supermassive black holes at M87’s center. After losing some of its outer stars, HVGC-1 largely remained intact as the black holes, as if a slingshot, flung the cluster out of the galaxy and into intergalactic space.