Declination +64° 20′ 36.226″ | Right ascension 18 21 57.2365 Redshift 0.2970 | |
Distance 3.4 gigalight-years (1.0 Gpc) | ||
H1821+643 is a quasar situated within the constellation of Draco. It is situated in a massive, strong cooling flow cluster. Astronomers in 2014 identified H1821+643 as the most massive black hole with a precisely measured mass, at 30 billion solar masses. Several other black holes are possibly more massive, but they have less accurate mass estimates. The Schwarzschild diameter of this black hole is about 172 terametres (1,150 AU), 28 times the diameter of Pluto's orbit.
References
H1821+643 Wikipedia(Text) CC BY-SA