Space and Physics

Black Hole Lined by String of Star Clusters


Janet Fang

Staff Writer

clockApr 2 2014, 03:43 UTC
580 Black Hole Lined by String of Star Clusters
Visible light (in blue) showing swirls of stars, green and aqua displaying a central emission with two jets, and newly discovered clusters are in red in the middle. A dot shows the location of the black hole (which can’t be seen) / Swinburne
Researchers have spotted huge clusters of young stars that look pearls on a string around a supermassive black hole in the center of a galaxy called NGC2110. 
Black holes like this one -- with condensations of matter so dense that light can’t even escape from its gravity -- are thought to be at the center of all large galaxies. The Milky Way has one that’s nearly four million times the mass of the Sun. NGC2110, in the constellation of Orion, is 120 million light-years away from us, and its black hole is about 100 times bigger than ours. 
Using the Keck Observatory in Hawaii, Mark Durré and Jeremy Mould from Swinburne University of Technology in Australia found four star clusters that are very close (well, close in astronomical terms) to a black hole.
“These star clusters hadn’t been seen before because they are hidden by dust clouds around the black hole and because they appear very tiny, but they can be observed in infrared radiation that penetrates the clouds,” Durré says in a press release. The Keck telescope also uses ‘adaptive optics’ to remove atmospheric shimmer, which can blur images. 
According to computer simulations, star clusters should form like beads or pearls on a string in a ring around the black hole -- exactly what they just observed. “After many millions of years, these clusters will be torn apart,” Durré adds, “and gradually settle into a central collection closer around the black hole.” 
Black holes don’t just suck in matter and energy; they also spew them out. Specifically, the black hole produces huge amounts of energy that come from the gas and dust that fall in. As the material funnels in, it hits the spinning ring of superheated gas around the rim of the black hole (this is called an accretion disk). Some of the matter that gathers in the disk ends up getting spewed out in speeding jets -- this is what gets observed by radio telescopes. 
As the black hole’s jets blast out that material, it feeds the cloud of gas and dust -- from which clusters of new stars can form. And it goes both ways. Once young stars in the cluster form, their radiation can feed and energize the black hole. 
This findings were published in Astrophysical Journal this week. 
Image: Via Swinburne

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