An unexpected discovery by astronomers using the National Science
Foundation's Karl G. Jansky Very Large Array (VLA) is forcing scientists to
rethink their understanding of the environment in globular star clusters,
tight-knit collections containing hundreds of thousands of stars.
The astronomers used the VLA to study a globular cluster
called Messier 22 (M22), a group of stars more than 10,000 light-years from
Earth. They hoped to find evidence for a rare type of black hole in the
cluster's center. They wanted to find what scientists call an intermediate-mass
black hole, more massive than those a few or more times the Sun's mass, but
smaller than the supermassive black holes found at the cores of galaxies.