Worlds of David Darling
Encyclopedia of Science
Home > Encyclopedia of Science

V404 Cygni

V404 Cygni
The best case for a stellar black hole. Observations at X-ray and optical wavelengths have shown that this is a binary system in which a late G or early K star revolves, every 6.47 days, around a compact companion with a probable mass of 8 to 15 solar masses, well above the mass limit at which a collapsed star must become a black hole. Most of the time the X-ray emission is quiescent, indicating only a slow trickle of material from the bright star onto the black hole's accretion disk.

In 2009, the distance to V404 Cygni was determined accurately by stellar parallax to be 7,800 460 light-years (2,390 140 pc).

Related categories