Can the 33 s pulsations observed from AE Aquarii be explained in terms of accretion onto the white dwarf surface ?

Abstract

The 33 s pulsing component observed from AE Aqr is frequently assumed to be the result of accretion onto the surface of a rotating white dwarf. The validity of this assumption is discussed in the present paper. I show that under the conditions of interest the white dwarf is in the state of supersonic propeller and the eciency of plasma penetration into its magnetosphere is < 0:1%. This is too small to explain the observed luminosity of the pulsing component. Moreover, I nd that for the currently established value of the angle between the magnetic and rotational axes of the white dwarf, the material entering the magnetosphere at the boundary can never reach its surface by flowing along the magnetic eld lines. I conclude that the assumption about the direct accretion onto the surface of the white dwarf in AE Aqr contradicts the observational data obtained in the optical/UV and thus cannot be accepted.