Encyclopedia > Cygnus X-1

  Article Content

Cygnus X-1

Cygnus X-1 (often abbreviated to Cyg X-1) is an X-ray source in the Cygnus constellation considered to be one of the most likely black hole candidates. The optical counterpart (HDE 226868) is 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).

Cyg X-1 is a binary star that contains a O9-B0 supergiant (with a surface temperature of 31000 Kelvin) 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.



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
Wheatley Heights, New York

... residing in the town. The population density is 1,433.7/km² (3,704.7/mi²). There are 1,494 housing units at an average density of 427.3/km² ...

 
 
 
This page was created in 26.9 ms