As a red giant evolves, its temperature decreases but its luminosity increases. As a white dwarf ages, its temperature decreases, and its luminosity also decreases. Why this difference?

Question

Quizplus · Accepted Answer

The expansion of a red giant as it cools is due to the decrease in temperature causing the outer layers of the star to become less tightly bound to the core. On the other hand, a white dwarf is supported by degeneracy pressure, which does not depend on temperature, so it maintains the same size as it cools. This means that a white dwarf's luminosity decreases as its temperature decreases, unlike a red giant, where the luminosity increases as the star expands.

As a Red Giant Evolves, Its Temperature Decreases but Its