Pulsations of a 4 Day Cepheid

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This animation illustrates the pulsation of a typical Cepheid variable star. This particular Cepheid is 1200 times a bright as our Sun, and 4 times as massive.
The pulsation cycle repeats itself every 4.2 days.

The radius varies from R = 2.26 to 2.52 x  1012 cm.
The temperature changes [T = 4250 to 5380 K] are represented by color variations.
The brightness (or magnitude) changes [~1 mag, a factor of 2.5] are represented by the color saturation ("whiteness").

Cepheid Pulsation

 Work supported by National Science Foundation.