"Magnetospheric gate" in polars

The mass-exchange process in polars is discussed. We point out that the strong magnetic field of a white dwarf in these systems can under certain conditions prevent the material from flowing through the L1 point operating as a "magnetospheric gate''. We show that the condition under which the "magnetospheric gate'' is closed is satisfied in the majority of polars known to date. This finding opens the question about a possibility to realize an alternative mechanism of mass exchange in these systems. We briefly discuss application of this mechanism to the best studied polars.