What are Cepheids?
Q: What are Cepheids?
A: Cepheids are a type of very luminous variable stars.
Q: What is the relationship between a Cepheid's luminosity and its pulsation period?
A: There is a strong direct relationship between a Cepheid's luminosity and its pulsation period.
Q: Why are Cepheids important standard candles for the galactic and extragalactic distance scales?
A: Cepheids are important standard candles for the galactic and extragalactic distance scales because of their relationship between luminosity and pulsation period.
Q: What are the several subclasses Cepheid variables are divided into?
A: Cepheid variables are divided into Classical Cepheids, Type II Cepheids, Anomalous Cepheids, and Dwarf Cepheids.
Q: Who discovered the first Cepheid known?
A: John Goodricke discovered the first Cepheid known, Delta Cephei, in the constellation Cepheus in 1784.
Q: Why is Delta Cephei of great importance?
A: Delta Cephei is of great importance because its distance is extremely well known, thanks in part to it being in a star cluster, and the precise Hubble Space Telescope/Hipparcos parallaxes.
Q: What is one way in which the rate of expansion of the Universe can be measured?
A: Cepheids are one of two ways in which the rate of expansion of the Universe can be measured.
