         cygnus&nbsp;x-1 (abbreviated cyg&nbsp;x-1) is a well-known galactic x-ray source and black hole candidate 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, producing a peak x-ray flux density of  (). cygnus&nbsp;x-1 was the first x-ray source widely accepted to be a black hole candidate and it remains among the most studied astronomical objects in its class. it is now estimated to have a mass about 14.8 times the mass of the sun and has been shown to be too compact 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 . cygnus&nbsp;x-1 belongs to a high-mass x-ray binary system about  from the sun that includes a blue supergiant variable star designated hde&nbsp;226868 which it orbits at about 0.2 au, or 20% of the distance from the earth to the sun. a stellar wind from the star provides material for an accretion disk around the x-ray source. matter in the inner disk is heated to millions of degrees, generating the observed x-rays. a pair of jets, arranged perpendicular to the disk, are carrying part of the energy of the infalling material away into interstellar space. this system may belong to a stellar association called 
Binary_stars Cygnus_(constellation) Henry_Draper_Catalogue_objects O-type_supergiants Objects_named_with_variable_star_designations Objects_within_10_kly_of_Earth Stellar_black_holes X-ray_binaries