In a tiny dwarf galaxy 110 million light-years away, astronomers have just found one of the smallest supermassive black holes ever seen.

"This black hole in Mrk 462 is among the smallest of the supermassive, or monster, black holes," said astronomer Jack Parker of Dartmouth College.

Its discovery suggests that supermassive black holes – some of them, at least – grow from stellar-mass seeds less than 100 times the mass of the Sun, rather than forming already large and growing larger.

This means we could expect relatively few dwarf galaxies to contain supermassive black holes, compared to the stellar seed model.

"Because buried black holes are even harder to detect than exposed ones, finding this example might mean there are a lot more dwarf galaxies out there with similar black holes," said astronomer Ryan Hickox of Dartmouth College.

"We can't make strong conclusions from one example, but this result should encourage much more extensive searches for buried black holes in dwarf galaxies," Parker said.