Different Types Of Supernovas
Enough supernovas have been observed to characterize some differences between them. Some supernovas have very little hydrogen associated with them (called Type-I supernovas), whereas others are hydrogen-rich (Type-II supernovas) and are associated with the star collapse or implosion described above. These two types of supernovas that have observationally different luminosity vs. time curves also have fundamentally different origins.
A Type-I supernova, also known as a carbon-detonation supernova, is produced from a white dwarf star that has gone through a number of nova events after accreting hydrogen and helium from a companion main sequence star and then burning the hydrogen to form helium. In some white dwarf binary star systems, each nova does not expel all of the accreted helium from around the core of the white dwarf, and eventually this builds up to a critical mass, at which point the star becomes unstable because the gravitational force exceeds the electron degeneracy force in the core, causing it to collapse and explode for a final time in a supernova. The mass at which a white dwarf binary system becomes unstable has been calculated to be about 1.4 solar masses, by Indian astronomer (and Nobel Laureate) Subramanyan Chandrasekhar, and is known as the Chandrasekhar mass. These supernovas are hydrogen-poor because there is very little hydrogen in the system when it explodes.
During the collapse of such a white dwarf to form a Type-I supernova, the star heats up to the point at which carbon begins to fuse into heavier elements almost everywhere throughout the star at the same time, causing the star to explode in a massive carbondetonation explosion that is comparable in violence to the Type-II supernova formed by the implosion of very massive stars. Type-I or carbon-detonation supernovas may also be caused by two white dwarf stars in a binary system that collide to form a massive unstable star that explodes in a supernova.
Continue reading here: Supernova Remnants
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