Horizontal-branch stars have a wide range of temperatures and luminosities between 50 and 100 times that of the Sun, so they are in what stage of their lives?

Question

Quizplus · Accepted Answer

Horizontal-branch stars are in the stage of core helium burning and shell hydrogen burning. This phase occurs after the red giant phase, when the core contracts and heats up enough for helium to begin fusing into carbon and oxygen, while hydrogen continues to burn in a shell around the core.

Horizontal-Branch Stars Have a Wide Range of Temperatures and Luminosities