Interpretation of light curves of the cataclysmic variable OY Car in a model with shockless interaction between a gaseous stream and the disk

To determine the parameters of the accretion disk and shock-wave region responsible for the formation of the orbital peak in the light curve of the binary system OY Car (an SU UMa-type variable), we have analyzed its U BV R and JK light curves using two gas-dynamical models with different regions of shock interaction: one with a hot line along the stream from the Lagrange point L1 and one with a hot spot on the accretion disk. The hot-line model can better describe the quiescent state of the system: the maximum X² for the optical light curves does not exceed 207, whereas the minimum residual for the hot-spot model is X²>290. The shape of the eclipse is almost identical in both models; the main differences are in interpreting out-of-eclipse portions of the light curves, whose shape can varyin the transition from one orbital cycle to another. The hot-spot model is not able to describe variations of the system’s brightness at orbital phases ?～0.1–0.6. The rather complex behavior of the observed flux in this phase interval can be explained in the hot-line model as being due to variations of the temperature and size of the system. Based on the analysis of a sequence of 20 B curves of OY Car, we conclude that the flux variations in the primary minimum are due to variations of the luminosity of the accretion disk, whereas the flux variability in the vicinity of the orbital peak is due to the combined effect of the radiation of the disk and hot line. The JK light curves of OY Car in the quiescent state and during a small flare also indicate preference for the hot-line model, since the primaryminimum and the flux near quadratures calculated using the hot-spot model are not consistent with the observations.