A very large star explodes, somewhere in the unfathomable space of our galaxy. The star's core collapses. The monstrous pressure crushes its atoms and smashes their electrons into the nuclei. There, the negatively charged protons change to neutrons and neutrinos. Billions of neutrinos particles, that have no electrical charge and little or no mass, escape through the star's outer shell into space. Traveling at nearly the speed of light, they penetrate clouds, reach Earth, and pass harmlessly through the bodies of millions of people and everything else in their ways.
A Supernova such as this occurs about once every 30 years in any one galaxy. At some time in their long lives, the supernova-spawned neutrinos of 20 million electron voltes or less interact with matter. These neutrinos include low energy electrons that give off light and can be detected in pure water.
are massive exploding giant stars. When the explosion occurs, the resulting illumination can be as bright as an entire galaxy. One of the most energetic explosive happenings known is a supernova. occur at the end of a stars lifetime, when its nuclear fuel is exhausted an it is no longer supported by the release of nuclear energy. If the star is particularly massive, then its core will collapse and in so doing will release a huge amount of energy. This will cause a blast waver that ejects the stars envelope into interstellar space. The result of the collapse may be, in some cases, a rapidly rotating neutron start that can be observed many years later as a radio pulsar. As a result of gravitational forces acting against the nuclear structure of the core of a fuel depleted star, tremendous shock wavers are generated which cause the outside layers of the star to be blown away from the core. This can happen in one of two ways depending on the type of supernova.
There are two main type of supernovae Type I and Type II then others branch off of these. The Type I involves two stars. One star is a white dwarf whose gravitational attraction is so intense that it is capable of siphoning off material from its companion. Unfortunately for the star, the white dwarf exceeds its Chandrasekhar limit of stability causing it to go into thermonuclear instability and produces one of the largest explosions known in the universe, the Type I SN. There are currently three types of Type I SN accepted by the astronomical community in general. The subclass types are basically determined by the state of the white dwarf's companion star, though to qualify as a Type I SN the companion should have released its hydrogen layer. They carry no spectroscopic evidence of hydrogen gas in the exploding material. Lack of oxygen indicates a beginning in highly evolved stars that have exhausted or ejected their hydrogen. Type II , while they also apparently derive from well-evolved stars, have abundant hydrogen in addition to the many other elements identifiable in their spectra. Current thinking is that Type Is result from rarer and much more massive stars then Type Is. Such stars with from about 8 times to as much as 50 times the mass of the sun, burn a sequence of heavier elements starting with hydrogen. Each supernova stage occurs at a suceedingly higher temperature and ...