Although many stars like our sun can remain stable for billions of years, more massive stars can race through their entire life cycles in a relatively short 10 million years or so, ending in a cataclysmic explosion called a supernova that literally tears the aging star apart. A supernova remnant is the expanding gaseous nebula created by these titanic explosions.
Supernova remnants are of interest to many areas of astrophysics.
Observations of the light from these objects provides our only direct test of the process of nucleosynthesis, whereby lighter elements are fused into heavier elements in the centers of stars. However, some supernova remnants remain visible for tens of thousands of years before finally blending back into the general interstellar medium, or tenuous gas in the regions between the stars. As a supernova shock wave travels outward from the point of the explosion, it sweeps up the gas of the interstellar medium into a roughly spherical, expanding shell. The light given off from these objects spans the entire electromagnetic spectrum from X-rays and ultraviolet light through the optical, infrared and radio. Hence, supernova remnants can be used as probes of the structure of the interstellar medium, as well as providing information on the physics of shock waves in conditions much different from those that can be created in a laboratory on earth.