Hello, I have read several articles/websites which talk about modelling white dwarfs, In all of these papers they state that it can be assumed the electrons have temperature zero, i.e. T<<T_fermi. I haven't been able to find a solid explanation of why this is approximation is possible, Is it due to the huge degeneracies in these stars which means that each of the electrons can reside in a ground state -> so their temperature can be considered as zero? I just think its strange that this assumption is possible considering the actual temperature of these stars is enormous. While I'm asking about things of this topic, I have also seen people state when E_fermi>>m_e c^2 relativistic effects become important. Is this because it implies the particles are moving very quickly?