The significant feature of a Cepheid variable is that there is a relationship between two intrinsic parameters,the first being easily measured,the second being the parameter that is required.These parameters are
A) variation of spectral color and distance to the star.
B) period of brightness variation and spectral color.
C) period of brightness variation and luminosity.
D) amplitude of brightness variation and luminosity.

Question

Quizplus · Accepted Answer

The significant feature of a Cepheid variable is that there is a relationship between the period of brightness variation and luminosity. The period can easily be measured, and from that, the luminosity can be determined. This relationship is known as the period-luminosity relationship and is used as a standard candle to measure distances in the universe. The other options are incorrect because the variation of spectral color and amplitude of brightness variation are not intrinsic parameters, and distance to the star cannot be directly measured from a Cepheid variable.

The Significant Feature of a Cepheid Variable Is That There