THE ULTRAVIOLET SPECTRUM AND PHYSICAL PROPERTIES OF THE MASS DONOR STAR IN HD 226868 = Cygnus X-1
THE ULTRAVIOLET SPECTRUM AND PHYSICAL PROPERTIES OF THE MASS DONOR STAR IN HD 226868 = Cygnus X-1
We present an examination of high-resolution, ultraviolet (UV) spectroscopy from Hubble Space Telescope of the photospheric spectrum of the O-supergiant in the massive X-ray binary HD 226868 = Cyg X-1. We analyzed this and ground-based optical spectra to determine the effective temperature and gravity of the O9.7 Iab supergiant. Using …