Cygnus X-1 is a very famous x-ray binary star system. It consists of a giant blue star (top) in orbit around what in all likelihood is a – wait for it – black hole. The black hole steals gas from its giant companion and that gas flows towards the black hole and then around it – to form what astronomers call an accretion disc. There is no bridge of matter between the objects, though, because the blue star is not sufficiently distorted. Instead, the accretion disc is created by material sucked in from the blue giant's immense stellar wind.