Over which of these stages of stellar evolution does the radius of a star remain approximately constant?

Question

Quizplus · Accepted Answer

During the main-sequence phase, a star is in a stable period of its life cycle where it fuses hydrogen into helium in its core, maintaining a balance between gravitational collapse and the outward pressure of nuclear fusion. This balance keeps the star's radius relatively constant. In contrast, during the red giant phase and the birth/initial formation stages, a star undergoes significant changes in size.

Over Which of These Stages of Stellar Evolution Does the Radius