All through the galaxy, we find stars that pulsate. Gravity makes stars
spherically symmetric. Because of this symmetry, we can describe the
pulsations with mathematical functions called spherical harmonics. The
patterns of these functions depend on two numbers, usually called the
spherical degree ("l") and the azimuthal order ("m").
The spherical degree changes the total number of hot and cool zones on the
surface. The azimuthal order can only be between "-l" and "+l", and
changes how the hot and cool zones are distributed on the surface of the
star.
From a distance, we can only see the brightness of a star change when the
spherical degree is small. Play with the values of "l" and "m" to see some
of the different ways stars can pulsate.
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