[Show abstract][Hide abstract] ABSTRACT: The prototype of accreting, pulsating white dwarfs (GW Lib) underwent a large amplitude dwarf nova outburst in 2007. We used ultraviolet data from Galaxy Evolution Explorer and ground-based optical photometry and spectroscopy to follow GW Lib for three years following this outburst. Several variations are apparent during this interval. The optical shows a superhump modulation in the months following outburst, while a 19 minute quasi-periodic modulation lasting for several months is apparent in the year after outburst. A long timescale (about 4 hr) modulation first appears in the UV a year after outburst and increases in amplitude in the following years. This variation also appears in the optical two years after outburst but is not in phase with the UV. The pre-outburst pulsations are not yet visible after three years, likely indicating the white dwarf has not returned to its quiescent state.
Preview · Article · Feb 2011 · The Astronomical Journal
[Show abstract][Hide abstract] ABSTRACT: Accreting pulsating white dwarfs offer the opportunity to study the effects of mass transfer, rotation and accretion on the internal structure of white dwarfs, as pulsation modes in white dwarfs penetrate deep into the stars. Thirteen of these systems are now known to reside in cataclysmic variables. These objects undergo large amplitude outbursts on 20-30 yr timescales which heat the white dwarfs and move them out of their instability zones for 2-3 yrs. Following the white dwarfs as they re-enter the instability strip thus allows an unprecedented opportunity to glean information about the modes and depth of heating. GW Lib and V455 And are two objects with accreting pulsating white dwarfs that underwent superoutbursts in 2007. We have followed these systems with ultraviolet data from GALEX and HST, and ground-based optical data. These 2 systems show different behavior, with GW Lib remaining hot and lacking pulsations 3 yrs post outburst, while V455 And shows a return of a group of periodicities present at shorter periods than pre-outburst. These differences are being studied on the basis of the masses and rotation rates derived from the COS data. Support for this work was provided by NASA GALEX grants NNX08AU43G, NNX09AF87G, HST grants GO-11638, GO-11639, and NSF grant AST-0607840.