Which of the following describes a star with a hydrogen-burning shell and an inert helium core?
A. It is a red giant that grows in luminosity until it dies in a planetary nebula.
B. It is a subgiant that gradually grows dimmer as its hydrogen-burning shell expands and cools.
C. It is a subgiant that grows in luminosity until helium fusion begins in the central core.
D. It is what is known as a helium-burning star, which has both helium fusion in its core and hydrogen fusion in a shell.
Answer:C
Which of the following describes a star with a hydrogen-burning shell and an inert helium core?
A. It is a red giant that grows in luminosity until it dies in a planetary nebula. B. It is a subgiant that gradually grows dimmer as its hydrogen-burning shell expands and cools. C. It is a subgiant that grows in luminosity until helium fusion begins in the central core. D. It is what is known as a helium-burning star, which has both helium fusion in its core and hydrogen fusion in a shell.