What is a Supernova Remnant?

A Supernova Remnant is the structure that remains after a massive star undergoes a supernova explosion.  It consists of the ejected matter from the former star, as well as interstellar dust and gas swept up in the associated shockwave. After a supernova occurs, the former star becomes a neutron star or black hole.

Good examples of supernova remnants include the Crab Nebula (M1) and the Veil Nebula (NGC 6992 and NGC 6960).