Analytical approximations and 2D hydrodynamical simulations are used to examine the interaction of supernova fragments with the internal structure of large multisupernova remnants (MSRs). The fragments are thermalized by reverse shocks generated in the interaction with the MSR interior, which is assumed to be hot and rarefied. The evolution is

IAUC 5738 available at Central Bureau for Astronomical Telegrams.

IAUC 5754 available at Central Bureau for Astronomical Telegrams.

Not Available

We present V-band CCD photometry, UBVRI photopolarimetry, and near simultaneous JHK photometry of 3C 345 during a renewed outburst in spring of 1992, which reached maximum at the end of April. The observations also show a large and variable polarization. There are very large variations in the position angle, unlike in previously published

It is shown that supernova explosions inside wind-driven cavities created by progenitors moving across the ambient medium result in a large diversity of remnant structures. In particular, barrel-like remnants can be explained as a result of an off-centered explosion within an almost spherical cavity, whereas explosions in strongly elongated