Let some star experience periodic surface pulsation at a practically constant temperature (i.e., at a constant brightness per unit surface of the star). With pulsation, the radii of the star in the extreme positions are in the ratio of 1: 2. What is the amplitude of the change in the total brightness of a star in magnitude?
The amplitude of the change in brightness corresponds to a change in the surface, i.e., a change in the square of the radius, since the star is a ball. The brightness changes, therefore, by a factor of 4 and the amplitude is 2.5 lg4 = 1.5 stars. magnitudes.
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