INTERACTION OF RAYLEIGH-TAYLOR FINGERS AND CIRCUMSTELLAR CLOUDLETS INYOUNG SUPERNOVA-REMNANTS

We discover a new dynamical mechanism that significantly enhances the growth of Rayleigh-Taylor fingers developed near the contact interface between the supernova ejecta and swept-up ambient gas in young supern ova remnants if the supernova remnant expands into a clumpy (cloudy) c ircumstellar medium. Our numerical simulation demonstrates that large Rayleigh-Taylor fingers can obtain a sufficient terminal velocity to p rotrude through the forward shock front by taking extra kinetic energy from vorticies generated by shock-cloud interactions. We suggest this mechanism as a means to generate the aspherical expansion of the supe rnova ejecta. Ambient magnetic fields are stretched and amplified as t he Rayleigh-Taylor fingers protrude, possibly leading to strongly enha nced radio emission. The material in the protrusions originates from t he ejected stellar material with greatly enhanced heavy elements. Ther efore, it can be a strong X-ray emitter. The timescale for the Rayleig h-Taylor fingers to reach the forward shock depends on the size, mass density, and distribution of clouds being engulfed by the supernova sh ock, although the details will require further numerical investigation .