The Cepheid "period-luminosity relation
" became a crucial link in the complex, interlocked cosmic distance scale by which astronomers were coming to measure distances throughout the wider universe.
He identified the first Miras in the Magellanic Clouds, leading to the discovery that these variables obey a tight period-luminosity relation (Glass & Evans, 1981).
A period-luminosity relation for Mira variables in the Large Magellanic Cloud, Nature, 291, 303- 304.
Systematic errors such as whether chemical composition differences among Cepheids might affect the period-luminosity relation
, will be examined using the infrared data.
(2) Distances are from the Hipparcos satellite except in the cases of MZ Aur, U Aur, TT Tau, and DV Tau, whose distances were estimated from spectroscopic measurements, and EU Tau, whose distance is from the period-luminosity relation
for Cepheid variables.
In 1907 Harvard astronomer Henrietta Leavitt discovered the famous Cepheid period-luminosity relation
. While examining variable stars in the Small Magellanic Cloud, she noticed that the brighter variables have longer periods.
Parallaxes were obtained for several types of pulsating variables, and data from 20 Cepheids will be used to reexamine the basic assumptions behind the period-luminosity relation
for these celestial yardsticks.
Some of the early photographic and visual catalog projects rivaled the Henry Draper Catalogue of spectra in accuracy and scope and led directly to the discovery of the interstellar medium, the Cepheid period-luminosity relation
, and precise maps of galactic structure.
Variations in the period-luminosity relation
induced by differences in chemical composition will be calibrated.