Features of the Matter Flows in the Peculiar Cataclysmic Variable AE Aquarii

TL;DR

This study investigates plasma flow structures in the AE Aquarii binary system, revealing how magnetic fields and turbulence influence matter transfer and system activity phases.

Contribution

It provides a numerical analysis of MHD equations showing the magnetic field's limited effect on laminar flow but significant impact during turbulence development.

Findings

Magnetic field does not hinder transient disk formation in laminar flow.

Turbulence enhances energy and angular momentum exchange, leading to matter escape.

Transition timescales match AE Aquarii's active and quiet phases.

Abstract

The structure of plasma flows in close binary systems in which one of the components is a rapidly rotating magnetic white dwarf is studied. The main example considered is the AE Aquarii system; the spin period of the white dwarf is about a factor of 1000 shorter than the orbital period, and the magnetic field on the white dwarf surface is of order of 50 MG. The mass transfer in this system was analyzed via numerical solution of the system of MHD equations. These computations show that the magnetic field of the white dwarf does not significantly influence the velocity field of the material in its Roche lobe in the case of laminar flow regime, so that the field does not hinder the formation of a transient disk (ring) surrounding the magnetosphere. However, the efficiency of the energy and angular momentum exchange between the white dwarf and the surrounding material increases considerably with the development of turbulent motions in the matter, resulting in its acceleration at the magnetospheric boundary and further escape from the system at a high rate. The time scales of the transition of the system between the laminar and turbulent modes are close to those of the AE\,Aqr transition between its quiet and active phases.