1999A&A...347..915I

The rapid braking on the white dwarf in the close binary AEAqr can be explained in terms of the pulsar mechanism provided the magnetic moment of the star µ>1.4x10³⁴G.cm³. Under this condition the magnetic field is strong enough to prevent accretion with the rate ≲10^–4.3M_☉/yr onto the white dwarf surface, so the traditional accretion-driven spin up mechanism cannot be applied to this system without additional assumptions. A scenario in which the initial magnetic moment of the white dwarf was essentially weaker than its present value is explored. A weakly magnetized (∼10⁴G) white dwarf was slowly spinning up by accretion of matter from its normal companion until its period P>P_cr≃20s. When the period had decreased beyond P_cr the white dwarf lost its angular momentum via the gravitational waves that caused strong differential rotation. The magnetic field inside the star was winding up on a time scale of a month up to ∼10⁸-10⁹G. This field manifests itself at the surface due to buoyant instability producing a surface field of 10⁷-10⁸G. As a result the white dwarf changed its initial accretor state to the presently observed ejector state, i.e. it is spinning down predominantly due to the magneto-dipole waves generation and particle acceleration.