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. We continue our study of spectral and photometric variability of Cyg X-1 on the basis of the 45-year long series of multicolor photometric observations and many-year-long series of spectral observations we have accumulated up to now. The mean level of star brightness continues to decrease since 1999 with the variations on smaller time scales superimposed. There is a connection between X-ray and optical changes. The chaotic variations of X-ray flux sometimes reaching to “hard” - “soft” state irregular changes switch on when U brightness decrease and He I λ 4713 Å absorption line depth increase. And inversely - they switch off during U brightness increasing and He I λ 4713 Å absorption line depth decreasing. This may be connected with star size variations, causing outflow gas instability. It is concluded that the fundamental parameters of the supergiant in the system of Cyg X-1 continue to vary on the time scales of years - decades.
VLT FORS 1 observations indicate the presence of a variable significant magnetic field in the X-ray binary Cyg X-1. The importance of this investigation comes from the fact that it rules one of the most significant BH manifestations: the X-ray millisecond flickering, usually related to reconnection of magnetic lines in the innermost part of the accretion disc.
Selected results of 1994-2004 optical photometric and high-resolution spectral observations including those obtained in the frame of a coordinated CIS countries campaign “Optical Monitoring of Unique Astrophysical Objects” and their comparison with ASM/RXTE X-ray data are briefly reviewed.
Detailed analysis of numerous observational data for Her X-1 / HZ Her shows that Her X-1 has a rare type of accretion regime: impulses of mass transfer every 0.81 d. Semi-empirical analysis show complicated 3 D type of gas flow near the outer disk rim of Her X-1: interaction of gas stream with disk forms blobs, which are disintegrated into small drops of matter (“sprays”) by an interaction with gaseous corona around the outer disk rim. Fall of the sprays on different parts of the disk decreases time of accreting mass flow along disk radius. Evaporation of sprays is a source of mass supporting the disk corona. The corona and disintegrated blobs (sprays) have numerous observational manifestations in optical and X-ray ranges. Evaporation of the corona from the Roche lobe could be an important source of orbital angular momentum loss and, consequently, a source of orbital period variation.
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