A Cepheid variable is a pulsating star whose period is tightly related to its luminosity, allowing its distance to be inferred from its measured period and apparent magnitude.
The pulsation period of a Cepheid variable is correlated with its absolute magnitude in a specified photometric band. Calibrating the relation with stars of known distance allows an observed period and corrected apparent magnitude to give a distance. Extinction and metallicity corrections matter for a precise cosmic distance ladder.
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A Cepheid variable is a type of star that exhibits regular and predictable variations in brightness over a specific period of time. These stars are essential for astronomers because their periodic brightness fluctuations are closely related to their intrinsic luminosity, allowing them to serve as important distance indicators in the universe. Cepheid variables are classified into two main types: **Classical Cepheids** and **Type II Cepheids**.