Variable star is actually an unusual binary system

Ars Technica : AR Scorpii was originally classified as a variable M-class star whose brightness varies over a period of 3.5 hours. However, an archive of images revealed additional variability beyond the originally observed periodicity. The star’s maximum brightness varied by up to a factor of four. A more careful observation of the star revealed that the star’s light alternated between being red-shifted and being blue-shifted over the same 3.5-hour period. The only explanation is the presence of a closely orbiting body roughly one-third as massive as the Sun—a white dwarf. The binary system also produces significantly more IR and radio emissions than would normally be expected. The extra light appears to be the result of photon emissions from extremely fast-moving electrons bombarding the M-class star. Researchers believe that the slowing of the white dwarf’s current high rate of rotation may be involved in whipping up the electrons.