Nova-produced Common Envelope: Source of the Nonsolar Abundances and an Additional Frictional Angular Momentum Loss in Cataclysmic Variables

A substantial fraction of cataclysmic variables (CVs) reveal nonsolar abundances. A comprehensive list of CVs that includes those that have been examined for these abundances is given. Three possible sources of these nonsolar abundances on the secondary are accretion during the red giant common envelope phase, an evolved main-sequence secondary, and nova-processed material. Use of the secondary’s cross section just on the escaping nova material to change the abundances of its convective region has been the killing objection for considering nova-processed material. The key element, ignored in other studies, is that a thermonuclear runaway on a white dwarf causes a strong propagating shock wave that not only ejects material but also produces a large amount of nonejected material that forms a common envelope. This nova-produced common envelope contains a large amount of nonsolar material. We demonstrate that the secondary has the capacity and time to reaccrete enough of this material to acquire a significant nonsolar convective region. This same envelope interacting with the binary will produce a frictional angular momentum loss, which can be the consequential angular momentum loss needed for the average CV white dwarf mass, the white dwarf mass accretion rates, the period minimum, the orbital period distribution, and the space density of CV problems. This interaction will decrease the orbital period, which can cause the recently observed sudden period decreases across nova eruptions. A simple, rapid evolutionary model of the secondary that includes the swept-up nova-produced material and the increasing convective region is developed and applied to individual CVs.