What is the procedure of a supernova?

Answer 1

As massive red supergiants age, they produce "onion layers" of heavier and heavier elements in their interiors. However, stars will not fuse elements heavier than iron. Fusing iron doesn't release energy. It uses up energy. Thus a core of iron builds up in the centers of massive supergiants.

Eventually, the iron core reaches something called the Chandrasekhar Mass , which is about 1.4 times the mass of the Sun. When something is this massive, not even electron degeneracy pressure can hold it up.

The core collapses. Two important things happen:

* Protons and electrons are pushed together to form neutrons and neutrinos.

Even though neutrinos don't interact easily with matter, at densities as high as they are here, they exert a tremendous outward pressure.

* The outer layers fall inward when the iron core collapses. When the core stops collapsing (this happens when the neutrons start getting packed too tightly -- neutron degeracy), the outer layers crash into the core and rebound, sending shock waves outward.

These two effects -- neutrino outburst and rebound shock wave -- cause the entire star outside the core to be blow apart in a huge explosion: a type II supernova!

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