Evolution of accreting white dwarfs; some of them continue to grow. (arXiv:1303.3642v1 [astro-ph.SR])

Evolution of accreting white dwarfs; some of them continue to grow. (arXiv:1303.3642v1 [astro-ph.SR]):
Novae are cataclysmic variable binary systems in which a white dwarf primary
is accreting material from a low mass companion. The importance of this
accretion takes on added significance if the WD can increase its mass to reach
the Chandrasekhar limit thus exploding as a Type Ia supernova. In this study we
accrete material of Solar composition onto carbon-oxygen white dwarfs of 0.70,
1.00 and 1.35 Msun with accretion rates from 1.6e-10 to 1.6e-6 Msun per yr. We
have utilized the MESA stellar evolution code for our modeling and evolve them
for many nova cycles or, in some cases, evolution to a red giant stage.
Differing behaviors occur as a function of both the WD mass and the accretion
rate. For the lower WD masses, the models undergo recurrent hydrogen flashes at
low accretion rates; for higher accretion rates, steady-burning of hydrogen
occurs and eventually gives way to recurrent hydrogen flashes. At the highest
accretion rates, these models go through a steady-burning phase but eventually
transition into red giants. For the highest white dwarf mass recurrent hydrogen
flashes occur at lower accretion rates but for higher rates the models exhibit
steady-burning interspersed with helium flashes. We find that for all our
models that undergo recurrent hydrogen flashes, as well as the steady-burning
models that exhibit helium flashes, the mass of the WD continues to grow toward
the Chandrasekhar limit. These results suggest that the accretion of Solar
abundance material onto carbon-oxygen white dwarfs in cataclysmic variable
systems, the single degenerate scenario, is a viable channel for progenitors of
Type Ia supernova explosions.