The changing period of a Cepheid variable tells us that the
A) star's luminosity is increasing.
B) surface temperature of the star is increasing.
C) hydrogen burning core has quit burning its nuclear fuel.
D) star is evolving.
E) star is about to undergo helium flash.

Question

Quizplus · Accepted Answer

The changing period of a Cepheid variable is related to its pulsation cycle, which is a result of the star's evolutionary changes. As the star evolves, its internal structure changes, affecting the pulsation period.

The Changing Period of a Cepheid Variable Tells Us That