Novae as a Mechanism for Producing Cavities around the Progenitors of SN   2002ic and Other SNe Ia
  We propose that a nova shell ejected from a recurrent nova progenitor system created the evacuated region around the explosion center of SN 2002ic. In this picture, periodic shell ejections due to nova explosions on a white dwarf sweep up the slow wind from the binary companion, creating density variations and instabilities that lead to structure in the circumstellar medium (CSM). Our model naturally explains the observed gap between the supernova explosion center and the CSM in SN 2002ic, accounts for the density variations observed in the CSM, and resolves the coincidence problem of the timing of the explosion of SN 2002ic with respect to the apparent cessation of mass-loss in the progenitor system. We also consider such nova outburst sweeping as a generic feature of Type Ia supernovae with recurrent nova progenitors. 
W. M. Wood-Vasey and J. L. Sokoloski