If a neutron star is more than 3 times as massive as the Sun, it collapses because a. the force of electron degeneracy is stronger than gravity. b. gravity overpowers the force of electron degeneracy. c. gravity overpowers the force of neutron degeneracy. d. the force of neutron degeneracy is stronger than gravity.

Neutron degeneracy is a quantum mechanical effect that helps to support neutron stars against gravitational collapse. When a star exhausts its nuclear fuel, it can no longer counteract gravity through fusion. In a neutron star, the primary supporting force against gravitational collapse is neutron degeneracy pressure. This pressure arises from the Pauli Exclusion Principle, which states that two identical fermions (such as neutrons) cannot occupy the same quantum state simultaneously. So, even under extreme conditions, neutrons resist being squeezed into the same space. This resistance provides the outward push that helps to keep the neutron star from collapsing.

Unlike electron degeneracy pressure in white dwarfs, neutron degeneracy pressure can support much larger masses. However, even this has its limit.

Gravitational collapse happens when an object can no longer support itself against the force of gravity. For neutron stars, this occurs when the mass exceeds a critical threshold. As gravity pulls the mass inward, the neutron degeneracy pressure tries to oppose this collapse. However, if the mass is too great (typically over three times the mass of the Sun), the neutron degeneracy pressure fails to stop the collapse.

During gravitational collapse, the core of the neutron star may continue to collapse into an even denser state, forming a black hole. This process involves extreme conditions where gravity overwhelmingly dominates other forces, creating an object with a gravitational pull so strong that even light cannot escape.

A supernova occurs when a massive star exhausts its nuclear fuel and experiences a core collapse, resulting in a powerful explosion. What remains after the explosion depends on the core's mass. For stars with mass below the Chandrasekhar limit, the result is a white dwarf supported by electron degeneracy pressure. For more massive cores, neutron stars form, supported by neutron degeneracy pressure.

The remnants of the supernova can include not only the neutron star or black hole but also a surrounding shell of gas and dust. This shell is made of material expelled during the explosion and can be observed as a glowing nebula. These supernova remnants provide valuable insights into the processes that govern the life cycle of stars and enrich the interstellar medium with heavy elements necessary for the formation of new stars and planets.

The Chandrasekhar limit is a critical concept in understanding stellar evolution and the end states of stars. This limit defines the maximum mass (approximately 1.4 times the mass of the Sun) that a white dwarf can have while being supported by electron degeneracy pressure. Beyond this limit, electron degeneracy pressure fails to counteract gravity, leading to further collapse.

For neutron stars, a similar but much higher threshold exists, often considered to be around three times the mass of the Sun. If a neutron star's mass exceeds this upper limit, neutron degeneracy pressure can no longer support the star, leading to gravitational collapse into a black hole. The Chandrasekhar limit highlights how the balance of forces in stars determines their ultimate fate, dictating whether they end up as white dwarfs, neutron stars, or black holes.