Interpretation of the radio emission from the supernova remnants Cas A and 3C 10

The observations of the young supernova remnants Cas A and 3C 10 are interpreted on the basis of a fluid dynamic model of the evolution of young supernova remnants. The shell structure and radio emission are explained in terms of instabilities arising at the boundary between the material ejected by the explosion and the interstellar medium. The model can explain many of the detailed features of the supernovae if the ratios of the mass of interstellar material swept up to that ejected are about 1 for Cas A and about 3 for 3C 10. These ratios lead to estimates for the energies of the original explosions of 5 × 10 44 J and 1 × 10 43 J, ejected masses of 2.5 M⊙ and 0.13 M⊙ and external particle densities of 2–3 cm −3 and 0.18 cm −3 for Cas A and 3C 10 respectively.