For the most part, black holes come in two varieties: small and jumbo. The small ones are the remnants of dead stars. They range from a few to about a hundred times the mass of the Sun. The jumbos inhabit the hearts of galaxies. They range from about a hundred thousand to several billion times the Sun’s mass. But there just isn’t much in the middle.

In fact, astronomers have logged only a few dozen medium-sized black holes. And many of those are controversial – they’re hard to confirm. Most of them are in other galaxies, so it’s hard to see their influence on the stars and gas around them.

One recent study may have added to the tally. Using observations designed to study dark energy, scientists said they discovered about 300 medium-sized black holes. About 70 of them inhabit the centers of small galaxies. Those black holes are gobbling gas and dust around them, making them brighter and easier to find.

Theory says there should be many more black holes in size “medium.” They may be the remnants of the ultra-massive stars that populated the early universe. Or they may have formed when dense clumps of gas collapsed under their own gravity. Either way, it’s possible that such black holes were the “seeds” from which the jumbo black holes grew.

For now, the search continues for these hard-to-find medium-sized black holes.

Script by Damond Benningfield