What happens to cores of main-sequence stars as they age?
A) They cool down because they run out of hydrogen fuel.
B) They cool down because they expand.
C) They heat up because they contract.
D) They heat up because helium is more tightly bound than hydrogen.

Question

Quizplus · Accepted Answer

As main-sequence stars age and consume their hydrogen fuel, the core contracts under gravity. This contraction increases the core's temperature and pressure, leading to further nuclear fusion reactions.

What Happens to Cores of Main-Sequence Stars as They Age