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Black Holes Encyclopedia

Alternate Names

IC 4625




in the constellation Ophiuchus


320 million light-years (98 megaparsecs)


870 million to 2 billion times the mass of the Sun


Diameter roughly equal to the diameter of Uranus' or Neptune's orbit around the Sun

Discovery Methods


Measuring the motions of stars

Because a black hole is both massive and compact, it exerts a strong gravitational pull on the material around it. Astronomers can deduce the presence of a supermassive black hole in the core of a galaxy by measuring the velocities of stars that orbit the black hole. A more-massive black hole will accelerate nearby stars to greater speeds, so the velocities of stars can reveal not only the presence of a black hole, but its mass as well.

More about black hole discovery methods »

This document was last modified: May 1, 2013.