Supernova. Computer artwork of a star exploding as a supernova and destroying its planets. This only happens to stars much more massive than the Sun, when they exhaust the hydrogen and helium that fuel their nuclear fires. It is the heat from such nuclear fusion processes that prevents the star collapsing under its own weight. Further nuclear fusion involving other elements is less efficient and destabilises the star. The core then collapses under its own weight. A rebounding shock wave from the super-dense core blows off the outer layers (as seen) at thousands of kilometres per second. These outer layers contain the heavy elements that are needed to form planets and life on them.