Clues for accretion discs and binary evolution from VY Scl stars

VY Scl stars are in two respects an extraordinary subgroup of CataclysmicVariables. First, they are located just above the period gap, the most prominentfeature of the orbital period distribution of CVs which indicates theirexceptional evolutionary status. Secondly, VY Scl stars show long lastinglowstates but no dwarf outbursts in their light curves which is still puzzlingin the context of the disc instability model (DIM). The aim of this proposal isto detect the one physical characteristic which relates to both, theevolutionary status of VY Scl stars and the mechanism driving their lowstates:the magnetic nature of the accreting white dwarf. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]