Pulsating variable stars

Definition

Pulsating variable stars are stars that vary in brightness due to periodic expansion and contraction in their outer layers. They are critical for measuring cosmic distances through their predictable luminosity changes.

5 Must Know Facts For Your Next Test

1. Pulsating variable stars include types such as Cepheid variables and RR Lyrae stars.
2. The period-luminosity relationship of Cepheid variables allows astronomers to determine distances to galaxies.
3. RR Lyrae stars have shorter periods than Cepheids and are often used to measure distances within our galaxy.
4. The variability in brightness is due to changes in the star's temperature and radius.
5. Henrietta Swan Leavitt discovered the period-luminosity relationship in Cepheid variables, which revolutionized distance measurement in astronomy.

Review Questions

• What types of pulsating variable stars are commonly used to measure cosmic distances?
• How does the period-luminosity relationship help astronomers determine distances?
• Who discovered the period-luminosity relationship, and why is it important?

Related terms

Cepheid Variables: A type of pulsating variable star with a well-defined period-luminosity relationship, useful for measuring longer cosmic distances.

RR Lyrae Stars: A type of pulsating variable star with shorter periods used primarily for determining distances within the Milky Way.

Period-Luminosity Relationship: The correlation between the pulsation period of a variable star and its absolute luminosity, key for calculating astronomical distances.