A Cepheid variable pulsates because compressing a component in its atmosphere causes this component to ionize and become opaque, thus trapping heat that later causes the star to expand. This atmospheric component is:
A)hydrogen.
B)helium.
C)carbon.
D)oxygen.

Question

Quizplus · Accepted Answer

Cepheid variables pulsate due to the ionization of helium in their atmospheres. When helium is ionized, it becomes opaque, trapping heat and causing the star to expand.

A Cepheid Variable Pulsates Because Compressing a Component in Its