On the Rayleigh-Taylor instability in stellar explosions

After a shock wave has accelerated the outer layers of a star during a stellar explosion, a rarefaction wave moves back into the stellar material, resulting in the conversion of internal energy into kinetic energy. This additional acceleration can be Rayleigh-Taylor unstable. Two-dimensional hydrodynamic calculations are presented for the case of Type II supernovae, showing that the instability results in the ejection of a clumpy shell. It is unlikely that radiation transport can damp the instability for normal Type II supernovae. We further conjecture that the structure of nova shells is a consequence of this instability; in this case, rings are formed by the smearing action of high rotational velocities.