Abstract
Abstract. 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.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Proceedings of the International Astronomical Union
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
