Three-Dimensional Numerical Simulation of a Flow Structure in the Asynchronous Polar CD Ind in the Approximation of an Offset Dipole Magnetic Field of a White Dwarf

Abstract

The flow structure in the asynchronous polar CD Ind was investigated in the approximation of an offset dipole. Computation results made it possible to identify such system features as the drift of hot spots over the white dwarf surface, the flow structure dependence on the phase of the beat period, and the magnetic pole switching. To study the flow structure, a three-dimensional numerical MHD model based on the approximation of modified magnetic hydrodynamics was used. Numerical calculations were performed for ten phases of the beat period at a constant rate of mass transfer. In addition, for a more detailed study of the poles switching, additional calculation series were carried out in the corresponding phase ranges of the beat period. The energy release zones during the spin-orbit period shift in longitude on average by 20°, which corresponds to 0.05 of the orbital period phase. The magnetic pole switching occurs in a time that does not exceed 0.1 of the beat period. In the middle of this process, accretion occurs on both poles with the same intensity, and the flow resembles an arch. Based on the calculation results, synthetic light curves were constructed for the optical range of the spectrum.