Electrodynamic Damping in Pulsating Stars

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Abstract
Small radial pulsations of stars are shown to be highly damped by electrodynamic forces when the star has a magnetic field unless the star is very diffuse. The author's theory of the permanent magnetic field of the sun indicates that the field is produced by regenerative means which is initiated by a small field arising from some more fundamental mechanism. The small initial field is probably produced by the rotation of the star combined with a separation of charge, although it may conceivably arise in other ways. Thus rotating stars will have a magnetic field and cannot pulsate, and conversely stars which pulsate can have no magnetic field and probably do not rotate. This is in accord with the idea that Cepheid variables, being youthful giants, are so large that they would be unstable under rotation. These considerations appear to remove the difficulties encountered by Eddington in his detailed theory of star pulsations.