The cooling of the white dwarf in VW Hyi.

Abstract

We present an analysis of the post-outburst evolution of VW Hyi based on the available IUE archive data. The spectrum closest to the previous outburst (~0.5days) shows a non-negligible contribution of a disc remnant while the white dwarf (WD) dominates the later observations. Following an outburst, the accretion-heated WD cools exponentially to a mean temperature T_wd_~19000K. The temperature decay time is significantly longer after a superoutburst (τ_S_=9.8days) than after a normal outburst (τ_N_=2.8days). Spectra obtained deep in quiescence (20 to 40 days past the previous outburst) show no further evolution. We demonstrate that a WD model with an inhomogeneous surface temperature and chemical composition can explain the observed metal absorption patterns.