So…What is a supernova? What are these intense energy explosions that radiate and emanate throughout the Universe? To answer this question In this instance well focus on the
type II supernovae SNII as this is the start that died. But your probably
wonder what a supernova Class I is (SNI).
In this instance the classifications that are used to describe
supernovae and their properties bear no real physical significance. But to
generalise, what the classifications mean, boils down to their spectra
(Spectrometric properties), So for example would be that when a dying star is
ready to explode, the explosion and the remnants from the explosion are analysed
spectrometric ally. It is these precise chemical characteristics that determine
which bracket to place the particular supernova into. Like whether an absorption
line is shown in a spectral analysis. Though normally when you discover a type
I SN. Normally it is similar in most ways to that of a white dwarf, though
still accreting matter and slowing perishing in the cold voids of space
eventually collapsing into itself. The SNI has to hit a certain threshold, a
mass threshold called the Chandrasekhar limit. The maximum mass allowed for a
white dwarf to be at, to avoid going supernova. A SNII is a final death phase,
where the star has reached the end of its life.
Fig.1 A extra terrestrial nebula that habits around Wolf-Rayet star (WR124)
Credit: van der Sluys, M,; Lamers, H. J. G. L. M. (2003).
*Note: This Nebula is 21,000 light years across
So, now you probably asking, why and how does a star
collapse in on itself? At first thought, it would seem like a difficult answer,
but actually is quite the contrary.
Gravity as usual, tries to pull anything down towards the particle or
object with most matter/density. For us to let go of a cup of tea in free space
only for gravity to intervene and pull it straight down to the ground, likely
breaking it and causing a mess. In that situation there is nothing stopping the
cup from falling to the Earth, no force or energy to keep it in check. With
Stars its similar, though there is a difference, energy! Energy is actually a
factor with a star and gravity. With the hydrogen and helium inside burring
away in a nuclear fusion reaction, intense energy is keeping gravity from
crushing the star into oblivion. Now, when the star dies, meaning when it has
no more hydrogen to burn and the fusion reaction is essentially gone, gravity
steps in to do its business, crushing the star into its inner most core. Then
the centre of the star then collapses on itself.
