Scientists seek better understanding of black holes from star cluster

The intrigue: Scientists were initially interested in the globular cluster of stars — named NGC 6397 — because they thought an elusive type of black hole known as an intermediate-mass black hole might be hidden within it.

• After studying data from the Hubble Space Telescope, however, the researchers behind the new study in the journal Astronomy & Astrophysics found that instead of one relatively large black hole at its center, NGC 6397 was actually hiding many smaller ones.
• Those black holes likely arose from the deaths of massive stars and migrated toward the center of the globular cluster because of their immense gravity, influencing other stars as well.
• Black holes within globular clusters could be a source of ripples in space and time called gravitational waves if they collide with one another.