Understanding Rogue Waves on Pulsating White Dwarfs
J.J. Hermes (University of North Carolina at Chapel Hill)

Kepler and K2 have uncovered a completely unexpected new physical phenomenon in pulsating stars: large-amplitude outbursts in the coolest ZZ Cetis (hydrogen-atmosphere pulsating white dwarfs). The outbursts are essentially rogue waves, sporadically increases the overall stellar brightness by up to 15%. We have now discovered four outbursting white dwarfs, all confined to a narrow range of temperatures at the red edge of the ZZ Ceti instability strip. These outbursts are providing fresh insight into pulsation energy transfer via nonlinear resonances, as well as the eventual cessation of pulsations in cool white dwarfs.