A self-colliding stellar wind model for SN 1979C

Abstract

SN 1979C shows significant deviations from the well-established Chevalier minishell model for the general, long-term radio light-curve behaviour. The implication is that the deviations are primarily due to fluctuations in the radio emission. In Chevalier's mini-shell model the radio emission is directly related to the density in the circumstellar shell which is established by mass-loss from the red supergiant progenitor star, suggesting that the deviations are the result of density variations in the shell. A possible mechanism which could account for such variations is the dynamical modulation of the red supergiant wind by a binary companion. In order to explore the feasibility of such a mechanism in relation to SN 1979C, we determine the associated circumstellar shells using numerical hydrodynamics and calculate radio light curves from the resulting shells using a modified mini-shell model. We compare these light curves with the observations and find that it is possible to account for the deviations from the standard mini-shell model, thus confirming the feasibility of the binary scenario.