Improved experimental resolution of the Vishniac overstability in scaled late-stage supernova remnants

Radiative shocks and blast waves are important in many astrophysical contexts, such as supernova remnant formation, cosmic ray production, and gamma ray bursts. Structure formation on radiative blast wave fronts in late-stage supernova remnants is expected to play a role in star formation via seeding of the Jeans instability. The origin of these structures is believed to be an instability described theoretically by Vishniac [1], which has been subject to continued numerical and experimental study. We report here on a series of experiments designed to examine the effect of magnetic fields on the Vishniac overstability. Preliminary results suggest that a strong transverse magnetic field appears to shift the overstability to longer wavelengths, which may have implications for gravitational star formation models. We present unmagnetized results from an experiment in progress which decomposes the spatial structure of the blast wave for quantitative analysis of magnetic and radiative effects.