Abstract

"GW Lib: a unique laboratory for white dwarf pulsations"

Odette Toloza (University of Warwick)

Boris Gaensicke, University of Warwick. JJ Hermes, University of Warwick.

Non-radial pulsations have been identified in a number of accreting white dwarfs (WDs) in cataclysmic variables (CVs). These stars offer insight into the excitation of pulsation modes in mixed H/He/Z atmospheres, and the response of these modes to changes in the WD temperature.

Among all pulsating CV WDs, GW Librae stands out by having a well-established observational record of three independent pulsation modes that were wiped out during its 2007 outburst. We have obtained new HST ultraviolet observations in May 2013 that show an unexpected behaviour: besides some activity near the ~280s period that has been observed in the past, the WD underwent a large-amplitude brightening. We demonstrate that the brightening is related to an increase of the photospheric temperature, rule out an accretion episode as explanation, and discuss this event in the context of non-radial pulsations on a rapidly rotating star.

Mode of presentation: poster