Supernovae,the explosive deaths of massive stars, are among the most momentous events in the cosmos because they disburse into space all of the chemical elements that were produced inside their progenitor stars, and including the elements fundamental for making planets and life. One course of supernovae (Type Ia) provides yet another benefit: these objects are considered to be standard distance candles. They result when enough material from an orbiting companion star falls onto the progenitor star to trigger it to explode.
Source: phys.org