Omega Centauri is the largest star cluster in the Milky Way, located over 15,000 lightyears from Earth. The star cluster is very old and thought to be the core of a galaxy that merged with ours. For many years, astrophysicists have thought a black hole to be the center of this cluster. However, until now, there has not been concrete evidence to confirm this.
PhD student, Max Gabriel, measured the movement of stars in the cluster from Hubble Space Telescope images that spanned 20 years. He realized that at the center of the star cluster there were seven stars moving very fast, so fast in fact that they should leave the cluster altogether. Anil Seth is University of Utah Physics and Astronomy professor and Gabriel’s advisor.
“What we think is happening is that there's a black hole at the center of the cluster and that's keeping the stars in orbits around the black hole. And so they can be moving really, really fast around that black hole and we can get a constraint on the mass. And that mass of the black hole is is really big. It's about 8000 times the mass of our Sun,” explained Seth.
The black hole at the center of Omega Centauri is particularly exciting to the scientists because it is an intermediate black hole. There are different types of black holes; stellar mass black holes are smaller, up to one hundred times the mass of our sun, and form from the explosion of a star. Supermassive black holes are generally more than a million times the mass of our sun and exist at the center of galaxies, like the milky way, and the origins of these are unknown.
“This object we found actually falls right in the middle of those camps. And we haven't really found any other good, for sure candidates before this, that's probably, scientifically, the most exciting part of of this finding,” Seth shared.
Seth and his collaborators have been studying the star cluster for years in hopes of furthering humanity’s understanding of the universe. Finding an intermediate black hole has great potential to answer questions about the origins of larger black holes, including supermassive black holes. Seth will be sharing these findings at the Clarke Planetarium IMAX theater in Salt Lake City at 7:00 pm on August 8th.
To hear more from Seth visit https://youtu.be/zbBelMTtaPQ
