Astronomers Find A Star Cluster Filled With Numerous Small Black Holes

Though most star clusters have a black hole at the center of their systems, astronomers were surprised to see a new cluster that actually had several small black holes in the middle rather than one large example of the mysterious space phenomenon.

According to, researchers came across the discovery after studying the movement of stars in the NGC 6397 using NASA’s Hubble Telescope and the European Space Agency’s Gaia spacecraft. The cluster is around 7,800 light-years away from earth.

The data suggested that the hidden mass at the cluster’s center, known as the “central dark component,” is filled with at least one “intermediate” black hole, as well more stellar-mass ones.

“The small effective radius of the diffuse dark component suggests that it is composed of compact stars (white dwarfs and neutron stars) and stellar-mass black holes,” wrote authors Eduardo Vitral and Gary Mamon, both of the Paris Institute of Astrophysics in France.

The stellar-mass black holes “should dominate the mass of this diffuse dark component, unless more than 25% escape from the cluster,” they added.

“Ours is the first study to provide both the mass and the extent of what appears to be a collection of mostly black holes in the center of a core-collapsed globular cluster,” Vitral concluded.

This discovery is exciting because it would be another piece of evidence that these mysterious smaller black holes exist. Though scientists have theorized about several possibilities of these intermediate black holes, they have technically not yet been discovered.

The new research is also important because the type of clusters of stars like NGC 6397 are often considered keys to understanding how the universe developed. In addition to being incredibly dense — therefore providing lots of material for astronomers — they are often as old as the universe itself. They are also rare, with only around 150 known examples in the Milky Way.

Moreover, the data will shed light on other types of aspects of astronomy as well. Physicists expect the black holes will slowly move towards the center of the star group and will eventually merge. Though this is many, many years away, it would give scientists a template of pre-merger conditions and how the mysterious objects act when joining one another. It would also offer insight into gravitational wave astronomy.

The discovery comes just months after the scientific world was rocked with an astronomical mystery. As was previously covered by The Inquisitr, one of the largest presumed black holes in the universe doesn’t actually seem to exist anymore in a bizarre twist for astronomers.

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