korrapäraselt pulseeriv muutlike tähtede tüüp, mille prototüüp on hele täht δ Cephei
a class of luminous, yellow, pulsating stars whose period of pulsation is closely related to their luminosity which changes very regularly with periods of 1 to 70 days between peaks
Cepheids are important cosmic benchmarks for scaling galactic and extragalactic distances; a strong direct relationship exists between a Cepheid variable's luminosity and its pulsation period.
The empirical correlation between the luminosity of a Cepheid variable and its period has been known to astronomers and used by them as a powerful distance determination method, for the better part of the 20th century.
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The stars are called Cepheids after the first star of this type to be discovered — Delta Cephei.
