HDE 226868 This star is the visual companion of the X-ray source Cygnus X-1. This binary system is located about 8000 light-years from earth and contains a black hole of at least 11 M_⊙ in orbit with HDe 226868, a B0 blue supergiant star. The photograph was taken with the 200-in. telescope at palomar observatory on palomar Mountain, north of San Diego. The slightly dimmer star above is an optical double that is not part of the binary system.