The first black hole ever discovered is more massive than previously thought
Cygnus X-1 is the heaviest stellar black hole observed without using gravitational waves
![illustration of Cygnus X-1 black hole slurping mass off companion star](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2021/02/021721_mt_black-hole_feat.jpg?fit=1030%2C580&ssl=1)
The famed Cygnus X-1 black hole (illustrated, slurping mass off its companion star) is nearly 1.5 times as massive as astronomers thought, new observations suggest.
International Centre for Radio Astronomy Research