Cygnus X-1

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Cygnus X-1 (often abbreviated to Cyg X-1) is an X-ray source in the constellation Cygnus, and considered to be a black hole. It is a high-mass X-ray binary, with the optical counterpart (HDE 226868) being a variable 8.9 magnitude star (visible with good binoculars in good observing conditions) at right ascension 19 h 56.5 min and declination of 35 deg 4 min (for 1950 epoch).

Tom Bolton identified Cygnus X-1 as a black hole using the facilities of the David Dunlap Observatory at the University of Toronto.

Cyg X-1 is a binary star that contains an O9-B0 supergiant (with a surface temperature of 31,000 kelvins) and a compact object. The mass of the supergiant is approximately 20–30 solar masses. The compact object has a mass of 7–13 solar masses; as the largest possible mass of a neutron star can not exceed three solar masses, it is believed to be a black hole. The X-rays are produced in an accretion disk that is formed by matter flowing from the supergiant into the black hole. Cygnus X-1 is the brightest persistent source of hard X-rays (E > 20 keV) on the sky. The distance to Cygnus X-1 is about 2500 parsecs.

Image:Cygnus-X-1.jpg

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Musical Connections

In 1977 Rush recorded a song about a fictional space voyage to Cygnus X-1. The song appears on the album A Farewell To Kings. A followup, Cygnus X-1 Book II: Hemispheres is featured on the 1978 Rush album Hemispheres, which explores the possibilities on the other side of Cygnus X-1, placing a much greater emphasis on symbolism. Bethany Curve's 1998 album Gold also included a track entitled Cygnus X-1. In 2001, Weezer demoed an instrumental song called "Cygnus X-1" for their fourth album Maladroit.