As Henrietta Swan Levitt discovered, a Cepheid's variability period relates directly to its luminosity. The longer the variability period, the more luminous the Cepheid.
What is the relationship between period and luminosity in Cepheid variables?
Cepheids are special in that the period at which Cepheids pulse is related to their average intrinsic luminosity. More luminous Cepheids pulse more slowly. By measuring the period of a Cepheid we can calculate its intrinsic luminosity, and thus its distance.
What is the relationship between luminosity and period?
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.
What is the period of a Cepheid variable related to?
luminosity Cepheid variable, one of a class of variable stars whose periods (i.e., the time for one cycle) of variation are closely related to their luminosity and that are therefore useful in measuring interstellar and intergalactic distances.
Do Cepheid variables have the same luminosity?
Classical Cepheids and type II Cepheids follow different period-luminosity relationships. The luminosity of type II Cepheids is, on average, less than classical Cepheids by about 1.5 magnitudes (but still brighter than RR Lyrae stars).
What is the period-luminosity relationship quizlet?
The period-luminosity relationship discovered by Henrietta Leavitt for Cepheid variable stars, relating variability to over-all brightness says that. the shorter the period, the lower the luminosity of the star. The event that settled the debate between Curtis and Shapley about the 'spiral nebulae' was.
Why is the period-luminosity relationship important quizlet?
Henrietta Swan Leavitt discovered the period-luminosity relationship. This relationship is critical because it tells us the longer the pulsation period, the more luminous the star.
Who discovered the period-luminosity relationship and why was it so critical?
Henrietta Swan Leavitt discovered the period-luminosity relationship. This relationship is critical because it tells us the longer the pulsation period, the more luminous the star.
What is special about Cepheid variable stars?
Cepheids Variables are special type of variable star in that they are hot and massive – five to twenty times as much mass as our Sun – and are known for their tendency to pulsate radially and vary in both diameter and temperature.
What does the luminosity of a main sequence star tell us quizlet?
Luminosity classes of stars are designated by Roman numerals and tell us what region of the H-R diagram the star falls in. We use both spectral type and luminosity class to completely classify stars; the spectral type tells us the star's temperature while the luminosity class tells us its radius.