Elusive medium-size black holes may form in dense 'birthing nests'

A blue scene with hazy bits of gas. In the middle-left of the image, there's a very sparkly blue area.

Researchers have discovered that elusive intermediate-mass black holes could form in dense star clusters containing anywhere between tens of thousands to millions of tightly packed stars called "globular clusters."

An intermediate-mass black hole has a mass between 100 and 10,000 suns. They're heftier than solar-mass black holes, which have a mass range between 10 and 100 solar masses, yet lighter than supermassive black holes, which have masses equivalent to millions or even billions of suns.