Novæ and Supernovæ
When massive stars die, they do so in a much more spectacular fashion. In one of the most energetic explosions in the universe, a supernova, a massive star gives its final performance as it dies. If one looks in enough other galaxies, one may find a great number of supernovae.
A nova, on the other hand, is not simply a small version of a supernova. It is an entirely different process, involving different objects. The the names of these objects have been poorly chosen. A nova is simply a relatively small surface event occurring on a white dwarf which has collected a bit of hydrogen from its binary neighbor and fused that hydrogen not unlike a hydrogen bomb going off. These novae tend to reoccur at more or less regular intervals.
When massive stars die, they do so in a much more spectacular fashion. In one of the most energetic explosions in the universe, a supernova, a massive star gives its final performance as it dies. If one looks in enough other galaxies, one may find a great number of supernovae.
Supernovæ come in two different varieties called, quite logically, type I and type II. Type I supernovæ are thought to be white dwarfs which are pushed over the edge of the Chandrasekhar limit, which is named in honor of Subrahyanman Chandrasekhar, who first used physics to calculate the value. The enlarged white dwarf would then become unstable and detonate. These are known as carbon detonation supernovæ. Type II supernovæ are massive red supergiant stars which have quickly evolved to the stage where many layers of nuclear fusion are found in the interior of the star. When the evolved star reaches iron fusion, the core collapses. On the rebound, we have a huge release of neutrinos and quite a bit of visible light as well. Most recently, astronomers were treated to a relatively nearby supernova in the Large Magellanic Cloud. Supernova 1987a has been fading since, and has left behind some interesting features, such as light rings. Other supernova remnants may be found throughout the sky.
Tycho discovered a nearby supernova in the sixteenth century. Kepler saw one just over thirty years later. It has been nearly four hundred years since the last supernova has been observed in our galaxy. When will the next observable supernova occur in our galaxy? Could be next year, could be next Tuesday, could be one hundred years from now. There is no way to be sure.
Nova
Accretion disk
Roche lobe
Nucleosynthesis
R process
S process
Designed and maintained by
.
Updated May 3, 2010