The presence of two black holes in a collection of stars known as globular clusters may be a common occurrence, according to researchers who say they may have identified a second black hole in a separate cluster known as M62.
"This implies that the discovery of the other black hole, in the globular cluster called M22, was not just a fluke," Laura Chomiuk, team member and MSU assistant professor of physics and astronomy, said in a statement. "Black holes really may be common in globular clusters."
The corpses of stars, black holes are anything but empty. "Rather, it is a great amount of matter packed into a very small area -- think of a star ten times more massive than the Sun squeezed into a sphere approximately the diameter of New York City," NASA explains on its site. The resulting gravitational field is so strong it sucks up everything that comes within its reach, including light.
For many years, astronomers believed black holes did not exist in globular clusters, which include some of the universe's oldest and densest groupings of stars packed together 1 million times more tightly than the region surrounding the Sun. Like commuters packed together on a train during rush hour, these stars inevitably bump into one another. If two black holes shared a place at the center, researchers believed, one would inevitably end up getting shoved out.
The discovery of a likely second example of such an occurrence, however, suggests not only is this is not the case, but that the phenomenon is in fact relatively common.
Said Chomiuk: "I think it's safe to say that we have discovered a whole new hunting ground for black holes."
The study was published in The Astrophysical Journal.