They are analogous to the Population II W Virginis stars, and on a Hertzsprung-Russell diagram, they lie above the RR Lyrae stars in the instability strip.
These objects exhibit a kappa mechanism associated with opacity changes due to conversion between singly- and doubly-ionized helium. They are analogous to the Population II W Virginis stars, and on a Hertzsprung-Russell diagram, they lie above the RR Lyrae stars in the instability strip. While observing some of these stars in the Magellanic Clouds, Henrietta Leavitt deduced a relationship between their luminosities and periods, allowing them to be used as standard candles for determining distances. For 10 points, name these pulsating variable stars.
These objects exhibit a kappa mechanism associated with opacity changes due to conversion between singly- and doubly-ionized helium.
{Cepheid} variables