The effect of asynchronism on wind-driven mass transfer rates in the polars

An asynchronous magnetic white dwarf affects the rate of orbital evolution in AM Herculis binaries. An over-synchronous star leads to a positive orbit al magnetic torque which reduces the rate of shrinkage of the secondary sta r's Roche lobe, and hence reduces the mass transfer rate. An opposing effec t occurs as a result of the orbital angular momentum loss via secondary mas s transfer in the absence of an accretion disc. The modification of the mag netic braking-driven synchronous mass transfer rate is calculated for a ran ge of degrees of asynchronism, and its effect is compared at different orbi tal periods.