Artist's concept of interacting binary polars

Interactive Binaries Show Signs of Induced Hyperactivity |  Astronomers studying highly energetic binary stars called polars have obtained the first observational evidence that the intense magnetic fields produced by the white dwarf half of the interacting pair can induce flares, sunspots and other explosive activity in its otherwise low-wattage, low-mass partner. NOAO Press Release 07-01

Image Credit: P. Marenfeld and NOAO/AURA/NSF