SIMBAD references

Many observations indicate that fast rotating late type stars show magnetic activity. We therefore argue that some of the secondary stars in cataclysmic binaries might also have magnetic fields. Such magnetic fields would reach over to the accretion disk around the white dwarf primary. We investigate the effect on dwarf nova outbursts. The magnetic field lines will penetrate the disk and remove angular momentum. This shifts the accumulation of mass towards the inner disk, closer to the white dwarf and therefore leads to a different outburst behaviour, which can be recognized in observed light curves of dwarf novae. We detected a cycle of 18 years in the outburst behaviour of SS Aur, possibly related to magnetic activity. SS Cyg displays a similar but less pronounced cycle of 7 years while no traces of magnetic activity were found for U Gem.