whats nova and super nova? whats the differnce?
do we have neutrin stars? what are they?
Say a star is in its red super gaint phase.[A star becomes a super gaint only if it is massive] .Once the end product of fussion Fe is attained suddenly the radiation at the core stops but the atmosphere & surface i.e. the planetary nebula still contains H2 thus the star suddenly losses matter giving rise to a super nova.This happens only for afew seconds .It is due to the over coming of the star's gravity by the radiation energy of the planetary nebula.During this a massive radio emmision can be observed on the spectrum.A large amount of matter is released to the interstellar space.This matter latter becomes a nebula.Then a neutron star is formed.[As far as I know ,atleast].
Consider a Binary star system [One star is massive (sun like)than the other is a small star].Say one star reaches its gaint state And the other is still stable .Matter starts moving from gaint to its companion encompassing it .the smaller star starts to swell ,its energy increases. Thus it attains gaint stage before it normally would.By the time it is a fully fludged gaint the massive companion would be a white dwarf.Now matter starts accumulating arround the dwarf . The smaller one looses the planetary nebula .But there still is stellar matter arround the dwarf.The energy is sufficient to sustain fussion and suddenly matter is liberated to the interstellar space. There is no strong shock wave as in a super nova [i think].
Basically Super nova is like an Explosion and a nova i more like a gaint flare.Nove appear quite frequently in our and other galaxies.But there has not been a super nova since 1904 when keppler observed it ,But then the concept of super nova was inexistant and they recorde it as a new star .After the advancement of radio technology to today's extent Astronomers & Astrophysicsts have calculated that in a galaxy like ours a super nova phenomenon has to occur atleast once in 300 years.So far they have been dissapointed.The astrophysicists, actually every physicist as a matter of fact is waiting eagerly for the occurance of a supernova to verify so many of the theories so far proposed.
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