Differential Rotation Mechanism for Energy Transfer in W UMa Binary

1 Introduction The explanation of the light curve of W UMa binary depends on the process of energy transfer. Recently, for this sort of binary, a lot of polarizations have been done to find out that many systems have their intrinsic polarizations whose Stockes parameters change with their orbital phase. It has been estimated that there exsits a magnetic field about 20 Gauss with EXOSAT, VLA simultaneous observations of XY Leo and VW Cep. So an MHD model for energy transfer in contact binary is suggested here and some important observational facts are explained.