A star in the instability strip pulsates because
A) the energy produced by the core is not constant.
B) the energy produced by the hydrogen burning shell is not constant.
C) the core of the star is composed of helium and degenerate electrons.
D) the surface temperature of the star is increasing.
E) density and opacity of the helium ionization zone changes with time.

Question

Quizplus · Accepted Answer

The pulsation of stars in the instability strip is primarily due to changes in the density and opacity in the helium ionization zone, which causes the star to expand and contract.

A Star in the Instability Strip Pulsates Because