Cataclysmic propellers
Prof. Peter Garnavich
Chair, Department of Physics
University of Notre Dame
For decades the cataclysmic variable star AE Aquarii has been an enigma. Its random flaring, broad emission lines, and fast-rotating white dwarf primary led theorists to model it as a "propeller" where gas donated by the cool dwarf was accelerated by the spinning magnetic field of the white dwarf and ejected from the binary. Recently a second propeller, J0240, was identified with observational properties similar to AE Aqr. But J0240 is viewed at high inclination resulting in eclipses of the flaring region and allowing a detailed test of the propeller model. In fact, the white dwarf in J0240 appears to have a spin period of just 25 seconds, the fastest spinning white dwarf in a CV system. These propellers offer clues to the origin of rapid rotation and the generation of strong magnetic fields on white dwarfs.