Astronomers discover two biggest black holes yet
An August 2009 photo of the Cygnus X-1 system, discovered in 1964, which consists of a black hole with a mass about 10 times that of the Sun in a close orbit with a blue, super-giant star with a mass of about 20 Suns.
Astronomers recently spotted the two biggest black holes ever seen in the universe.
"For comparison, these black holes are 2,500 times as massive as the black hole at the center of the Milky Way galaxy, whose event horizon is one-fifth the orbit of Mercury," study co-author Nicholas McConnell, a graduate student at the University of California, Berkeley, told Space.com. His team’s findings will be published in the journal Nature on Dec. 8.
One black hole is located in the galaxy NGC 3842, around 320 million light years from Earth; it has a mass about 9.7 billion times the mass of our Sun, the Guardian reported. The second black hole is about 336 million light years from Earth, located at the center of the galaxy NGC 4889; it has a mass of about 21 billion Suns.
According to Space.com:
The scientists used the Gemini and Keck observatories in Hawaii and the McDonald Observatory in Texas to monitor the velocities of stars orbiting around the centers of a pair of galaxies. These velocities reveal the strength of the gravitational pull on those stars, which in turn is linked with the masses of the black holes lurking there.
“Measurements of these massive black holes will help us understand how their host galaxies were assembled, and how the holes achieved such monstrous mass,” McConnell told the New York Times.
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