A star cluster has broken away from a galaxy and is hurtling in the direction of Earth at more than 2,000,000mph, US astronomers have discovered. The Harvard-Smithsonian Center for Astrophysics discovered the hypervelocity cluster, named HVGC-1, by chance and have no idea why it was catapulted out of galaxy M87.
But one theory is M87 – which is one of the biggest galaxies in the nearby universe and weighs as much as six trillion Suns – has two massive black holes at its centre. The star cluster may have wandered too close and was then flung like a slingshot at tremendous speed on a fast journey to nowhere. But don’t panic, scientists believe its fate is to drift through the void between galaxies until the end of time.
Nelson Caldwell, lead author of the study, said astronomers have found runaway stars before, but this is the first time they have found a runaway star cluster. It was only through a stroke of luck that HVGC-1 was spotted, he said.
The team spent years studying space around M87, separating star clusters from individual stars and galaxies by colour. They then used the MMT Telescope in Arizona to examine hundreds of clusters in detail, with a computer calculating the speed of each one. Any oddities were examined by hand, and most turned out to be errors.But HVGC-1 was different and its surprisingly high velocity was real, said study co-author Jay Strader, from Michigan State University.
“We didn’t expect to find anything moving that fast,” he said.
HVGC-1 is hurtling so fast it may have already left M87 and be sailing out into intergalactic space. Star clusters are relics of the early universe, and usually contain thousands of stars crammed into a ball a few dozen light-years across.