1.LUTH,Observatoire de Paris, CNRS, Université Paris-Diderot,Meudon,France;2.Laboratoire de Mathématiques,Université Paris-Sud,Orsay,France;3.CEA-DAM-DIF,Arpajon Cedex,France
Abstract:
The Vishniac instability is supposed to explain the fragmentation of the thin shell of shocked matter in the radiative phase
of supernova remnants. However its implication and its consequence on the morphological evolution of stellar systems is not
fully demonstrated. The present paper tackles this subject by numerical simulations and focus on the role of the adiabatic
index in the instability growth. The HYDRO-MUSCL 2D hydrodynamics code has been used to simulate the evolution of a supernova
remnant thin shell and the triggering of the Vishniac instability in this thin shell. We have studied the temporal behavior
of the perturbation. The first result of the numerical study is the existence of the Vishniac instability in the simulations.
This result is proved by the overstability process observed in the simulations as predicted by the theoretical analysis. The
second important result is the damping of the perturbation at late evolution and for all the set of parameters. Indeed the
accretion of matter onto the shock damps the instability when theoretical analysis predicts its occurrence.