As a white dwarf star gradually cools, its radius stays approximately constant. What is happening to the white dwarf's luminosity?
A) It stays the same.
B) It increases.
C) It increases then decreases periodically.
D) It decreases.
E) You can't tell from the information given.

Question

Quizplus · Accepted Answer

As a white dwarf cools, it will no longer be able to maintain nuclear fusion reactions in its core. Without fusion, the star's luminosity will decrease over time. However, the radius remains constant because the core becomes increasingly degenerate, meaning that the electrons are packed more tightly together and the star's overall density increases. This increase in density offsets the decrease in luminosity, so the radius remains approximately constant.

As a White Dwarf Star Gradually Cools, Its Radius Stays