DECELERATION OF SUPERNOVAE IN THE CIRCUMSTELLAR WIND AND THEIR RADIO-EMISSION

A model for the deceleration of a supernova shell in the circumstellar wind in the thin-layer approximation is used to analyze the evolution of the radio emission of the supernovae SN 1980K, SN 1979C, and SN 19 87A. Spectroscopic data on the expansion velocities of the outer bound ary of the shell are also used. No significant differences were found between a description of the evolution of SN 1980K based on the standa rd self-similar solution and the numerical model considered here. In t he case of SN 1979C, the self-similar solution cannot fit the evolutio n of the expansion velocity, whereas the numerical model for this supe rnova satisfactorily describes the dynamics of the shell expansion. Th e numerical model cannot reproduce the radio evolution of SN 1979C ove r a timespan of 12 years simultaneously at all frequencies if the wind parameters are constant along the radius. In 1987A, the early evoluti on of the radio emission and expansion velocity cannot be accounted fo r by free-free absorption in the wind, but a model with synchrotron se lf-absorption is consistent with both the radio data and the expansion velocity.