The dwarf elliptical galaxy was seen about 54 million light years away from the Milky Way galaxy, in which Earth is situated.

This is only the second time a supermassive black hole has been discerned in a dwarf galaxy, and only the third time that astronomers have observed a double nucleus at the heart of a galaxy, said Dr Debattista in a press release posted on the Astronomy Department website at the University of Washington.

The galaxy, called VCC128, lies in the Virgo Cluster and is about one per cent the size of the Milky Way.

“All of its stars combined would equal 100 million to one billion of our suns,” said Dr Debattista.

Black holes lie in the centre of many galaxies, and have gravitational fields so powerful that nothing – not even light – can escape. A supermassive black hole is so large that its mass equals anything between 100,000 and 10 billion of our suns.

The team of researchers were sifting through archived data from the Hubble Space Telescope when they found the black hole. They were studying the nuclei of dwarf galaxies, which are thought to form from globular clusters – tightly packed spherical collections of stars that orbit a galaxy.

As they examined the properties of the nuclei, they discovered that one galaxy, VCC128, had a double nucleus. They then determined the double nucleus is made up of two points of light from stars collected at opposite edges of a ring surrounding a black hole.

“The fact that we found a black hole is impressive because it has been thought that a galaxy this small would not be able to host a black hole. It has been speculated that dwarf galaxies like this could not make black holes,” Dr Debattista said.

The findings are included in a poster detailing the discovery, co-authored by Dr Debattista and four other researchers.