magnetic cataclysmic variables
magnetic cataclysmic variables(mag-net -ik kat-ă-kliz -mik) A class of cataclysmic variables in which the large magnetic field of the white dwarf (of order 103 tesla) affects the rotation of, and the accretion of material onto, the white dwarf. Two types can be distinguished: in polar systems (also known as AM Herculis stars) the white dwarf is in synchronism with the orbital period (i.e. the white dwarf's spin period is the same as the orbital period); in intermediate polar systems (also known as DQ Herculis stars) the spin period of the white dwarf is typically 10 times shorter than the orbital period. In both types, the accretion flow is channeled along the magnetic field lines directly onto the polar cap of the white dwarf. Accretion disks are generally absent in the case of polars, but may be present in the case of intermediate polars. See also mass transfer.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006