Smallest known galaxy has supermassive black hole
The black hole is five times the mass of the one at the center of the Milky Way galaxy. It is inside one of the densest galaxies known to date, the M60-UCD1 dwarf galaxy that crams 140 million stars within a diameter of about 300 light-years, which is only 1/500th of the galaxy's diameter.
Inside this dwarf galaxy, the night sky would dazzle with at least 1 million stars visible to the naked eye.
The finding implies there are many other compact galaxies in the universe that contain super-massive black holes. The observation also suggests dwarf galaxies may actually be the stripped remnants of larger galaxies that were torn apart during collisions with other galaxies rather than small islands of stars born in isolation.
"We don't know of any other way you could make a black hole so big in an object this small," said University of Utah astronomer Anil Seth, lead author of an international study of the dwarf galaxy published in Thursday's issue of the journal Nature.
Seth's team of astronomers used the Hubble Space Telescope and the Gemini North 8-meter optical and infrared telescope on Hawaii's Mauna Kea to observe M60-UCD1 and measure the black hole's mass.
The black hole at the center of the Milky Way galaxy has the mass of four million suns ■
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