A polar is a highly magnetic type of cataclysmic variables containing an accreting white dwarf and a low-mass donor star. Due to the magnetism, the white dwarf would synchronously spin, however, there are still several asynchronous polars well confirmed with their angular velocities of the white dwarfs more or less than their orbital ones.
Click here for original story, Researchers identify periods in asynchronous polars
Source: Phys.org