The Effects of Magneto-convection on Short Period Cataclysmic Variables

Abstract Many of the current problems related to the evolution of Cataclysmic variables (CVs) revolve around the magnetic nature of the main sequence secondary. It is known that magnetic fields alter the structure of low mass stars. In particular, they inhibit convection, leading to inflated radii. Here we present a simple model to demonstrate the impact of magneto-convection (MC) on the evolution of short period CVs. We find that the inclusion of MC leads to larger secondaries, longer orbital periods and smaller mass-loss rates. When including magnetic effects, the minimum orbital period is increased by 14 minutes, indicating that this could help alleviate the period minimum problem in CV evolution. We also examine the effect of the white dwarf (WD) mass on the minimum period. While increasing the WD mass does increase the minimum period, it is not substantial. Therefore it is unlikely that the period minimum problem can be solved with a larger WD mass or with mass growth of WD.