in the constellation Sextans
400 million to 2 billion times the mass of the Sun
Diameter probably equivalent to the size of Uranus' orbit around the Sun
The black hole at the center of the galaxy NGC 3115 is one of the largest and most-massive yet discovered: It probably weighs in at around one billion times the mass of the Sun.
The galaxy itself is several times larger than the Milky Way. Its stars are mostly old, and there is little gas to give birth to new stars. That also means there is little gas to feed the black hole, so there is no big, bright disk surrounding it.
Early in the galaxy's history, though, vast reserves of gas may have poured into the black hole, powering a "quasar" -- an object brighter than an entire galaxy of stars, but no bigger than our solar system. Quasars were common in the early universe, but as they used up the gas and dust around them, they shut down, so there are few quasars found in the more modern universe.
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This document was last modified: November 19, 2009.