Published online by Cambridge University Press: 12 April 2016
In an earlier paper [1], we demonstrated that the declining ultraviolet flux, observed long after optical quiescence was reached in three dwarf novae, most likely represents the cooling of a white dwarf whose outer layers have been heated by the accretion event. If the observed change in temperature is due to the cooling of the white dwarf surface layers following the intense heating produced in the outburst, then a thermal timescale of the heated portion of the white dwarf is implied, which could yield a rough estimate of the depth of heating into the white dwarf envelope. The thermal timescale is essentially given by the ratio of the internal energy in the affected layers to their luminosity, L.