We present a detailed study of the active eclipsing binary V455 Cygni (V455 Cyg), based on spectroscopic and photometric data from the 1.25-m and 0.6-m telescopes at the Crimean SAI Observatory and the 0.6-m telescope at the Maidanak Observatory, collected in the period from 2000 to 2010.
Spectroscopic evidence and the shape of the light curves suggest the existence of a geometrically and optically thick accretion disc around the more massive and hotter gainer. We used a model of the binary system based on the Roche geometry and including the accretion disc with active regions to estimate the orbital and physical parameters of the components of V455 Cyg. Our model fits the observations very well for all individual passband light curves.
The evident seasonal changes in the shape of the light curves, including prominent variations in the depth of the eclipses, can be explained by the changes in the parameters of the accretion disc and the active regions of the disc, arising in turn from a variable rate of mass transfer.