Physical process which shapes Cassiopeia A

The paper describes the physical process which shapes the Cassiopeia A nebula. Cassiopeia is a remnant of a recent supernova event (AD 1680) within our own galaxy. The source's structure and time evolution have been studied through a series of three high-resolution radio images spanning four years. The images reveal tenuous clumps of intermediate velocity stellar ejecta which are continuously puncturing, from within, the decelerated shell swept up by the diffuse ejecta which once had the highest velocity. (UK)