Multicolor Photometry of a Close Binary System with an X-ray Source

Abstract

Four-color WBVR photoelectric observations of close binary system (CBS) HZ Her = Her X-1 in 1986–1994 are presented. Two-color diagrams (W–B)–(B–V) and (B–V)–(V–R) are given, which make it possible to study the behavior of the accretion disk (AD) near the main minima of binary system Min I and Min II. When constructing the light curves in all filters from the orbital phase in all phases of the precession period, the array of observations was processed considering the matrix of the X-ray source. A quantitative and qualitative interpretation of the results is given using the model of the precession of an AD of a neutron star (NS) in the direction of orbital motion of the system (direct precession). When interpreting the observational material, one of the existing models is considered, within which one can satisfactorily explain the heterogeneity of the gas flow, “hot spot,” as well as the existence of individual splashes that move along independent Keplerian trajectories around the outer parts of the NS AD of Her X-1. Using the matrix of time switching on X-ray emission of a NS and the partitioning of all series of the author’s optical observations into a specific cycle of switching on X-ray emission from a relativistic object provide a more realistic picture of CBS behavior, as well as to identify fine photometric effects occurring in it in different states.