Circumstellar interaction of the type Ia supernova 2002ic

We propose a model to account for the bolometric light curve, the quasi-continuum and the Ca II emission features of the peculiar type Ia supernova (SN) 2002ic, which exploded in a dense circumstellar envelope. The model suggests that the SN Ia had the maximum possible kinetic energy and that the ejecta expand in an approximately spherically symmetric (possibly clumpy) circumstellar environment. The Ca II and the quasi-continuum are emitted by shocked SN ejecta that underwent deformation and fragmentation in the intershock layer. Modelling of the Ca II triplet implies that the contribution of the OI 8446-Angstrom line is about 25 per cent of the 8500-Angstrom feature on day 234, which permits us to recover the flux in the Ca II 8579-Angstrom triplet from the flux of 8500-Angstrom blend reported by Deng et al. We use the Ca II doublet and triplet fluxes on day 234 to derive the electron temperature (approximate to4400 K) in the Ca II line-emitting zone and the ratio of the total area of dense fragments to the area of the shell, S/S-0 similar to 10(2). We argue that Ca II bands and the quasi-continuum originate from different zones of the shocked ejecta that reflect the abundance stratification of the supernova.