A black hole with a mass 15.65 times that of our Sun has entered the record books as the biggest stellar black hole found so far. Astronomers found the black hole in a galaxy called Messier 33, which is about 3 million light years from Earth.

Investigations led by Jerome Orosz, an Associate Professor at San Diego State University's astronomy department, also revealed that the black hole - known as M33 X-7 - orbits a companion star with a mass 70 times that of our sun. This companion star has also gained the distinction of being the most massive companion star in a binary system containing a black hole.

A paper on M33 X-7 appears in today's issue of the journal Nature. Jeffrey McClintock of the Harvard-Smithsonian Center for Astrophysics, Orosz's co-author on the paper, notes that the black hole's companion star will also eventually go supernova, resulting in a pair of black holes.