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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. This characteristic of classical Cepheids was discovered in 1908 by Henrietta Swan Leavitt after studying thousands of variable stars in the Magellanic ...
Cepheid variables may pulsate in a fundamental mode, the first overtone, or rarely a mixed mode. Pulsations in an overtone higher than first are rare but interesting. [ 2 ] The majority of classical Cepheids are thought to be fundamental mode pulsators, although it is not easy to distinguish the mode from the shape of the light curve.
The nearby Cepheid variables were population I stars with much higher metal content than the distant population II stars. As a result, the population II stars were actually much brighter than believed, and when corrected, this had the effect of doubling the estimates of distances to the globular clusters, the nearby galaxies, and the diameter ...
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.
Type II Cepheids are not as well known as their type I counterparts, with only a couple of naked eye examples. In this list, the period quoted for RV Tauri variables is the interval between successive deep minima, hence twice the comparable period for the other sub-types.
A nearly vertical region of the HR diagram, known as the instability strip, is occupied by pulsating variable stars known as Cepheid variables. These stars vary in magnitude at regular intervals, giving them a pulsating appearance.
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Cepheid variables are one of the most important classes of pulsating star. They are core-helium burning stars with masses above about 5 solar masses. They principally oscillate at their fundamental modes, with typical periods ranging from days to months.