When a massive star dies in a supernova explosion, its gases are ejected in all directions into space. Eventually, the gas may condense and combine with interstellar hydrogen to create new stars. But long before that happens, we can glimpse snapshots of how such explosions change as they age by studying objects at various phases of evolution.
Supernova 1987A in the Large Magellanic Cloud is in the earliest years of such an explosion. In time, a compact expanding region of stellar debris looks