Question

What causes a high mass star to become a supernova? What type of remnant(s) will be left behind in this case? What is meant by electron degeneracy and neutron degeneracy?

Answer 1

Most of the stars in the solar system are sustained (stopping them from collapsing) by the Nuclear fusion reactions occurring at its core. The energy produced from this fusion supports this huge mass from collapsing against its own gravity. When the star runs out of fuel it ceases to generate fusion energy at its core. As a result, the stars collapse into itself due to gravity until it reaches a critical mass and undergoes a thermonuclear explosion which is termed as a supernova.

N.B. The collapsing star meets either of the two fates- it collapses to form a neutron star or a black hole; or a white dwarf.

A supernova remnant (SNR) is the aftermath of a supernova explosion. It consists of material (mass) ejected in the explosion. This explosion creates a shock wave that sweeps up interstellar material from the exploded star. The huge energy reminiscent from these explosions tends to be a source of powerful X ray and audio emitters which last for several thousands of years.

Electron degeneracy is nothing, but Pauli’s exclusion principle applied to interstellar bodies. No two electrons can occupy identical states even under the enormous pressure of a collapsing (“dying”) star. For small stellar masses gravitational collapse energy is insufficient to produce neutron from neutron star, hence collapse is stopped due to electron degeneracy and the collapsing star forms white dwarfs.

Neutron degeneracy is also an interstellar application of Pauli’s exclusion principle. No two neutrons can occupy identical states even under the enormous pressure of a collapsing (“dying”) star. For large stellar masses gravitational collapse energy is enough to produce neutrons by combining electrons and protons. Further collapse of the star fills up all the lowest neutron energy level and they are forced to move to higher energy levels. This creates a pressure which prevents further collapse of the star and the collapsing star forms a neutron star.