Star wars: Hubble captures remains of shredded galaxy around rare new kind of black hole
Astronomers using NASA's Hubble Space Telescope have found hot young stars clustered around the first 'intermediate-mass' black hole ever discovered.
The young, blue stars suggest that there might have once been a dwarf galaxy there, now shredded. The black hole weighs as much as 20,000 suns, and was first detected in 2009.
Scientists believe that these 'intermediate' black holes might merge to form supermassive black holes, like the monster at the heart of our own Milky Way, with a mass the same as four million suns.
The black hole is surrounded by a cluster of bright young blue stars - which leads the Hubble astronomers to suspect it might have shredded a galaxy around it
The discovery could lead to a new understanding of how supermassive black holes - and the galaxies around them - form. Most galaxies are thought to have a black hole at their heart.
'For the first time, we have evidence of the origin of this middle-weight black hole,' said Mathieu Servillat, who worked at the Harvard-Smithsonian Center for Astrophysics.
It's thought that the stars around it formed after its dwarf galaxy collided with a much larger galaxy, ESO 243-49, in the process stripping away many of it the dwarf galaxy's orginal stars.
Astronomers know how massive stars collapse to form stellar-mass black holes, weighing about 10 times the mass of our sun, but it's not clear how supermassive black holes form.
One idea is that supermassive black holes may build up through the merger of smaller, intermediate-mass black holes weighing hundreds to thousands of suns.
Supermassive black hole: A very long Chandra observation of the region around the Sgr A*, the black hole at the centre of the Milky Way, our own galaxy. Scientists think that the new discovery could lead to an understanding of how supermassive black holes form
Lead author Sean Farrell, of the Sydney Institute for Astronomy in Australia, discovered this unusual black hole in 2009 using the European Space Agency's Newton X-ray telescope.
Known as HLX-1 (Hyper-Luminous X-ray source 1), the black hole weighs in at 20,000 solar masses and lies towards the edge of the galaxy ESO 243-49, 290 million light-years from Earth.
Farrell and his team then observed HLX-1 simultaneously with NASA's Swift observatory in X-ray and Hubble in near-infrared, optical, and ultraviolet wavelengths.
The intensity and the color of the light shows a cluster of young stars, 250 light-years across, encircling the black hole.
'This black hole is unique in that it's the only intermediate-mass black hole we've found so far. Its rarity suggests that these black holes are only visible for a short time,' said Servillat.