Artist’s View of a Black Hole in a Globular Cluster

Black Holes Unexpectedly Discovered in Globular Clusters M15 and G1

These two globular star clusters, M15 and G1, harbor hundreds of thousands of stars. But deep within their dense cores is an unexpected guest: a class of intermediate-sized black holes. Black holes are invisible, but the probing eye of NASA's Hubble Space Telescope found them by...

Globular Cluster M15

Globular Cluster M31 G1

Using Spectroscopy to Measure Velocity Dispersion

Relation of Black Hole Mass to Cluster Mass

Relative Location of M15 and M31 G1

Evidence for Existence of a Black Hole

Location of M15 and M31 G1 in the Northern Autumn Sky

Location of Globular Cluster G1 in Galaxy M31

Black Hole in a Globular Cluster

Space Science Update: Hubble Discovers Black Holes in Unexpected Places