Study of the rapid variability of a dwarf nova SS Cyg at different brightness levels

Abstract

Observations of the dwarf nova SS Cyg were made in the period 2019–2021 at different brightness values (V~ 10–12m) both at the stage of falling radiation flux after the flare maximum, and in the inactive state between flares. Data were obtained in filtersRc(~8650 observations, 3 sets), andV(~50 000 points, 22 sets). The value of the system’s orbital period in 2019–2021 (Porb= 0.27408(2)d) used in this study is 0.4% less than the value obtained in 1983–1996. The time resolution between two successive measurements is 6–14 s depending on the equipment used. An extensive database of new observational data allowed us to perform a quantitative analysis of observations. Analysis of the data after taking into account orbital variability and other trends associated with changes in the system’s radiation flux during the night showed the presence of cyclic fluctuations in brightness, usually 4–10 events per orbital cycle — flickering. For most series of observations, the Lafleur-Kinman method determined such a value of the oscillation period at which convolution of observations with it showed a single wave. The obtained values of the characteristic flickering times and their amplitudes show their dependence on the average brightness level of the system. With increasing luminosity of the system, both of these quantities decreased linearly. From the component size ratios SS Cyg it was shown that the source of flickering is located in the region of interaction of the gas flow with the near-disk halo: only this region in the SS Cyg system with parameters (q,i,Rd), defined by the authors earlier, can be eclipsed at large radii disk, and is clearly visible in all other orbital phases of the system.