Abstract: An attempt is made to explain the observed surface temperatures and luminosities of cataclysmic variable white dwarfs based on the cooling physics and time-averaged structure of the white dwarf in response to accretion. The evolutionary changes in core temperature and core luminosity as an accreting white dwarf evolves quasi-statically are compared with the cooling evolution of a nonaccreting, one solar mass, pure C-12 core. Then, the evolutionary behavior of the white dwarf envelope in mass and temperature, in response to long-term accretion, is used to predict temperatures and luminosities of white dwarfs during quiescent intervals between nova outbursts. It is shown that the observed luminosities and effective temperatures of the bare white dwarfs detected in some cataclysmic variables are the expected intrinsic values associated with classical nova thermonuclear outburst cycles. Two alternate interpretations of their observed surface temperatures and luminosities are assessed.

Abstract: It is notoriously difficult to determine the semiamplitude of the white dwarf in a cataclysmic binary (Smak 1970). This is a result of the fact that spectral features arising in the photosphere of the white dwarf are rarely, if ever, seen in the spectra of these systems. The motion of the white dwarf must be inferred from radial velocity variations of the broad emission lines which originate in the surrounding accretion disk. This would not propose any particular problem if the disk emissivity was axially symmetric. Unfortunately, this is usually not the case, primarily because of enhanced emission in the vicinity of the shock front (hot spot) where the interstar mass transfer stream impacts the disk. The challenge, then, is to measure the velocity of the emission lines using a method which is insensitive to contamination from the hot spot. The purpose of this paper is twofold: (1) to review a simple method of measuring the velocity of emission lines in cataclysmic binaries and (2) to remind the reader of the disastrous consequences which can arise if care is not exercised when measuring the emission line velocities.

Abstract: Carbon-oxygen white dwarfs may be the progenitors of type-I supernovae. Spherically-symmetric models of such dwarfs have been evolved from an artificial core incineration. The convectively unstable incinerated region was allowed to grow at a velocity prescribed by the mixing-length theory of convection. The mixing length can be varied to give different cases. In all the cases considered the dwarfs exploded and were totally disrupted. The calculations were stopped after the dwarf matter had gone into homologous expansion. The model with the best estimated mixing length incinerated 0.8M⊙. The energy released in burning this amount of carbon-oxygen to56Ni provides a disrupted dwarf with velocities suitable for type-I supernovae.

Abstract: It is now well established that the eruptions characteristic of dwarf novae result from changes in the luminosity of the accretion disc centred around the white dwarf component of these systems. These luminosity variations are most successfully accounted for by variations in the accretion flow through the disc but the mechanism responsible for this accretion modulation remains unsettled.