Star Clusters Home to Midsize Black Holes

Astronomers have detected what could be a “missing link” in the development of the universe: midsize black holes that are neither supermassive nor as small as a single exploded star.

The middling black holes were spotted using the Hubble Space Telescope in two globular star clusters in Earth’s celestial neighborhood, astronomers said.

While astronomers have known for years about vastly large black holes and rather small ones, said Steinn Sigurdsson, who attended a NASA news conference on the find as an independent commentator, “We didn’t know if we could get from one to the other or if they were completely unrelated, and this seems to be the step that takes us from one to the other.”

Black holes are unimaginably dense regions in space whose gravitational pull allows nothing to escape. For that reason, black holes are invisible but can be detected by the pattern of swirling stars and gas around their edges.