Cepheid variable
Videos
A Cepheid variable is a type of variable star that pulsates radially, varying in both diameter and temperature. It changes in brightness, with a well-defined stable period and amplitude.
RS Puppis, one of the brightest known Cepheid variable stars in the Milky Way galaxy (Hubble Space Telescope)
Illustration of Cepheid variables (red dots) at the center of the Milky Way
Light curve of Delta Cephei, the prototype of classical cepheids, showing the regular variations produced by intrinsic stellar pulsations
Period-luminosity relation
Videos
In astronomy, a period-luminosity relation is a relationship linking the luminosity of pulsating variable stars with their pulsation period.
The best-known relation is the direct proportionality law holding for Classical Cepheid variables, sometimes called the Leavitt Law. Discovered in 1908 by Henrietta Swan Leavitt, the relation established Cepheids as foundational indicators of cosmic benchmarks for scaling galactic and extragalactic distances.
The physical model explaining the Leavitt's law for classical cepheids is called kappa mechanism.
