Ami S. Glasner, Eli Livne, James W. Truran
We present here, for the first time, a 2D study of the undershoot convective
mechanism in nova outbursts for a wide range of possible compositions of the
layer underlying the accreted envelope. Previous surveys studied the mechanism
only for solar matter accreted on top of a carbon oxygen white dwarf. Mixing
with carbon was found to be crucial for the process since it dramatically
enhanced the burning rates. According to observations and stellar evolution
theory, in classical and recurrent novae the outermost underlying layer of the
white dwarf can also be composed of ONe or pure Helium. In all the cases we
examined we found significant amounts of mixing. We present the details of the
burning rates and the convective flow for each underlying layer and discuss its
significance for the long term debate as to the exact mechanism responsible for
the enrichment of novae ejecta. Our results show that the undershoot convective
dredge up model predict mixing amounts that can be consistent with observations
in all the cases we examined, including helium enrichment in recurrent novae.
View original:
http://arxiv.org/abs/1111.6777
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