Glossary · Thiên văn học
Supernova
The powerful explosion of a star. There are two main mechanisms: the core of a massive star collapses once it has nothing left to fuse, or a white dwarf in a binary system explodes after pulling in material from its companion.
Core-collapse supernovae (Type II, for example) happen in stars more than about 8 times the mass of the Sun. Once the core is essentially all iron, nothing is left to fuse for energy, so the core collapses and then rebounds, sending a shock wave outward that blows the star apart. What remains of the core becomes a neutron star, or a black hole if the original star was very massive.
Type Ia supernovae happen in binary systems. A white dwarf gains material from its companion; as its mass approaches the Chandrasekhar limit of about 1.4 solar masses, carbon and oxygen in its core begin to fuse uncontrollably. The explosion leaves no core behind. Observations of very distant Type Ia supernovae were the basis of the 1998 discovery that the expansion of the universe is accelerating.
Elements made in the star's core and in the explosion itself are thrown out into space, where they mix with the interstellar medium.