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Pulsating Stars - Windows to the Universe

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# Pulsating Stars

 Spherical degree l = 1 l = 2 l = 3 Azimuthal order m = -1 m = 0 m = +1 m = -1 m = 0 m = +1 m = -1 m = 0 m = +1 m = -2 m = -1 m = 0 m = +1 m = +2 m = -2 m = -1 m = 0 m = +1 m = +2 m = -2 m = -1 m = 0 m = +1 m = +2 m = -2 m = -1 m = 0 m = +1 m = +2 m = -2 m = -1 m = 0 m = +1 m = +2 m = -3 m = -2 m = -1 m = 0 m = +1 m = +2 m = +3 m = -3 m = -2 m = -1 m = 0 m = +1 m = +2 m = +3 m = -3 m = -2 m = -1 m = 0 m = +1 m = +2 m = +3 m = -3 m = -2 m = -1 m = 0 m = +1 m = +2 m = +3 m = -3 m = -2 m = -1 m = 0 m = +1 m = +2 m = +3 m = -3 m = -2 m = -1 m = 0 m = +1 m = +2 m = +3 m = -3 m = -2 m = -1 m = 0 m = +1 m = +2 m = +3
##### Images from Asteroseismology.org
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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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support!