Astronomers with access to Hubble Space Telescope data have reported finding a giant black hole in one of the smallest known galaxies.

The black hole has a mass of 21 million suns – it is five times greater than the one at the center of the Milky Way – and was discovered in a dwarf galaxy known as M60-UCD1.

The findings published in the scientific journal Nature suggest that dwarf galaxies may be remnants of larger ones that have been torn apart during collisions, in places of small islands of isolated stars.