Moderate asphericity of the SN 2002ic circumstellar envelope

The polarization of the supernova SN 2002ic interacting with a dense circumstellar envelope is calculated in the context of the asymmetric version of a previously proposed spherical interaction model. The circumstellar envelope is taken to be oblate. The observed polarization can be reproduced for an aspect ratio of 0.65-0.7, assuming inclination angles of > 60 degrees. This model predicts a weak sensitivity of the line profiles to the orientation, which is in agreement with the absence of significant variations of the line profiles among SN 2002icYlike supernovae. We propose a test for distinguishing between the binary and single-star progenitor scenarios on the basis of the polarization distribution function for the growing sample of these events.