If the sun and stars are supported by gas pressure, what supports a white dwarf?
Answers
White Dwarfs are supported by electron degeneracy pressure .
Explanation:
The degeneracy pressure is a kind of pressure that appears as a result of Pauli Exclusion Principle, a purely quantum mechanical effect.
I can try explaining what this degeneracy pressure is. But understanding this requires some basic ideas from quantum mechanics.
You can see a white dwarf as a gravitational potential well, confining free electrons - which are fermions. So the system can be modelled as fermionic particles in a box. Particles like electrons cannot have arbitrary energy. Energy is quantised in quantum mechanics and the allowed discrete values of energies are arranged into energy states. Fermions are subject to the Pauli Exclusion Principle, according to which there can be no more than two electrons in a energy state (corresponding to two different spin states).