Astronomers have found the biggest black hole ever measured — it's 40 billion times the sun’s mass, or roughly two-thirds the mass of all stars in the Milky Way. The gargantuan black hole lurks in a galaxy that’s supermassive itself and probably formed from the collisions of at least eight smaller galaxies.
Holm 15A is a huge elliptical galaxy at the center of a cluster of galaxies called Abell 85. A team of astronomers captured a snapshot of Holm 15A’s stars in orbit around the galaxy’s central black hole and created a model to help them calculate the black hole’s mass. The team described their findings in a recent paper posted to the preprint site
arXiv and set to be published in
The Astrophysical Journal.