Why does a white dwarf's degeneracy pressure not drive the core hot enough to restart fusion?
Answer
Degeneracy pressure is largely independent of temperature, preventing the contraction needed to raise temperatures sufficiently.
Unlike thermal pressure, which increases with temperature, electron degeneracy pressure resists compression based on density, not thermal state. Therefore, as the dwarf cools and contracts slightly, the pressure does not increase in a manner that generates the necessary heat for fusion reignition.
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