Results of high-resolution optical spectroscopy investigation of Cyg X-1 = V1357 Cyg
Abstract:Selected results of optical high-resolution spectral observations (in 1997 and 2002-2004) are briefly reviewed. A comparison with ASM/RXTE X-ray data is made. The photometric and spectral variations point to supergiant parameter changes on a timescale of tens of years. Line profile non-local thermodynamic equilibrium simulations lead to the conclusion that the star radius increased about 1-4% from 1997 to 2003-2004 and the temperature decreased by 1300-2400 K.
Document Type: Research Article
Affiliations: 1: Astronomical Institute, Russian Academy of Sciences, Moscow, Russia 2: Radiophysical Research Institute (NIRFI), Nizhny Novgorod, Russia 3: Sternberg Astronomical Institute, Moscow, Russia 4: International Centre for Astronomical, Medical and Ecological Research, Terskol, Russia 5: Korean Astronomy Observatory, Optical Astronomy Division, Daejon, South Korea 6: Bohyunsan Optical Astronomy Observatory, Jacheon POB, Young Chun, KyungPook, South Korea 7: Astronomy Department, Kazan State University, Tatarstan, Russia 8: Crimean Astrophysical Observatory, Nauchny, Crimea, Ukraine
Publication date: February 1, 2007