Hubble Space Telescope: Kepler's Supernova Remnant (visible-light data)

As the shock ploughs into material lost from the progenitor star after the initial supernova explosion, instabilities left in its wake cause the swept-up gas to fragment into clumps. The Hubble data also show thin filaments of gas. These filaments reveal where the shock wave is encountering lower-density, more uniform interstellar material.