Cygnus X-1
Cygnus X-1 (abbreviated Cyg X-1) is a well-known galactic X-ray source. It is thought to be a black hole in the constellation Cygnus.
It was discovered in 1964 during a rocket flight, and is one of the strongest X-ray sources seen from Earth. Cygnus X-1 was the first X-ray source accepted as a black hole. It is among the most studied astronomical objects in its class. The compact object is estimated to have a mass about 14.8 times the mass of the Sun.[1] It is too small to be any known kind of normal star, or other likely object besides a black hole. If so, the radius of its event horizon is about 44 km.
Cygnus X-1 Media
X-ray image of Cygnus X-1 taken by a balloon-borne telescope, the High-Energy Replicated Optics (HERO) project
A blue-band light curve for Cygnus X-1, adapted from Kemp et al. (1987)
A Chandra X-ray spectrum of Cygnus X-1 showing a characteristic peak near 6.4 keV due to ionized iron in the accretion disk, but the peak is gravitationally red-shifted, broadened by the Doppler effect, and skewed toward lower energies
An artist's impression of the HDE 226868–Cygnus X-1 binary system
NASA's "Galaxy of Horrors" poster for Cygnus X-1
