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

Question

Quizplus · Accepted Answer

During the main-sequence phase, the energy is balanced due to the energy generated by hydrogen fusion in the core and the energy radiated from the surface. This equilibrium leads to a relatively constant radius of the star. In other phases of stellar evolution, such as the red giant phase or the asymptotic giant branch phase, the radius can increase significantly. The birth and initial formation phase are not included in the choices because it is a short-lived phase and not a significant factor in determining the radius of a star.

Over Which Stage of Stellar Evolution Does the Radius of a Star