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How Stars Die
Exploring one of the most intriguing mysteries of the universe
The stability of a star is dependent upon the balance between the gravitational pull and the combustive pressure exerted by the fusion of its gases. When these forces no longer match, the result is destabilization and loss of equilibrium.
When fuel resources run out, some stars start consuming hydrogen from other stars around them to maintain their own stability. This enables them to survive longer than they otherwise would.
When a star approaches the end of its lifespan, there is a loss of mass that is as singularly bizarre as it is dramatic.
First, the amount of dust released is enough to cover the entire scope of the dying star. This is what makes us see it dimming right before it explodes.
This is also why when we look into outer space, we see nebula — the dust and gas cloud that typically exists between stars. Nebula is usually invisible unless illuminated by either bright clouds or the light that stars emit.
To determine whether a star becomes darkest just before it disintegrates, that star would have to be studied before and after its demise, and this is not something that has been done yet.
The core and the outer layer
As the core expands, the fusion of hydrogen in the outer layers decreases, leading to an overall decrease in energy. Thus the star itself starts to contract, though the surface temperature keeps rising.
The result is an increase in the fusion rate of the remaining hydrogen. The hydrogen fuel is burned to keep the core intact.
As soon as this supply has been consumed, the core caves in from the pull of gravity, but leaves some fusion still taking place in the outer layers.
As the helium core continues to heat up and the fusions continue, the star may swell into a ‘red giant’. At this stage, the helium burns along with the hydrogen.
The explosions that take place could go on for many years before the core completely collapses. The collapse takes place at the point where there is no fuel remaining.
