Time-Dependent Models for a decade of SN 1993J
  A classical and a relativistic law of motion for a supernova remnant (SNR) are deduced assuming an inverse power law behavior for the density of the interstellar medium and applying the thin layer approximation. A third equation of motion is found in the framework of relativistic hydrodynamics with pressure, applying momentum conservation. These new formulas are calibrated against a decade of observations of \snr. The existing knowledge of the diffusive processes of ultrarelativistic electrons is reviewed in order to explain the behavior of the `U' shaped profile of intensity versus distance from the center of SN 1993J. 
Lorenzo Zaninetti
astro-ph.GA