CYG X-1 = V1357 CYG investigation based on high-resolution optical spectroscopy of 2002–2004
We report the results of Cyg X-1 spectral monitoring for 2002–2004. A comparison of observed and non-local thermal equilibrium model profiles for H I, He I and Mg II is given, taking into account the tidal distortion of the Cyg X-1 optical component and its illumination by X-ray emission from the secondary component. We set limits on the main characteristics of the optical component, T eff =30 400±500K and log g =3.31±0.07, and on the overabundances of He and Mg, [He]/[H]=0.43±0.06 dex and [Mg]/[H]=0.75±0.15 dex. The Doppler images were reconstructed by an improved Doppler tomography method on the basis of nine He II (?=4686 Å) profiles from 2003 (the ‘soft' X-ray state) and six profiles from 2004 (the ‘hard' X-ray state). This allowed us to set limits on the black-hole-to-supergiant mass ratio (1/4)= slant M X / M O = slant (1/3).
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Document Type: Research Article
Astronomical Institute of the Russian Academy of Science, 48 Pyatnitskaya Street, Moscow, 119017, Russia
Radiophysical Research Institute (NIRFI), 25, Bol'shaya Pecherskaya Street, Nizhny Novgorod, 603600, Russia
Sternberg Astronomical Institute, 13 Universitetskij Prospekt, Moscow, 119992, Russia
IC AMER, Terskol, 361605, Russia
Korean Astronomy Observatory, Optical Astronomy Division, 61-1 Hwaam-dong, Yuseong-gu, Daejeon, 305-348, South Korea
Bohyunsan Optical Astronomy Observatory, Jacheon POB, Youngchun, Kyungpook, 770-820, South Korea
Astronomy Department, Kazan University, 18 Kremliovskaya Street, Kazan, 420008, Russia
Tartu Observatory, 61602 Toravere, Tartumaa, Estonia
Publication date: 2005-10-01
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