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Paper: Shocking Remarks on Stellar Pulsation
Volume: 479, Progress in Physics of the Sun and Stars
Page: 355
Authors: Gough, D. O.
Abstract: Smoothly varying sound waves steepen as they propagate, at a rate that is an increasing function of the amplitude of the wave. If they are not first absorbed or otherwise dissipated by diffusion, the waves eventually shock. One might expect, therefore, that the steepening process in the outwardly propagating component of a normal acoustic pulsation mode in a star might permit the wave to escape more easily into the atmosphere, thereby leaking energy in an amplitude-dependent manner. Is this the process that limits low-amplitude intrinsically overstable pulsations such as occur in roAp stars? Even if the waves do not shock below the location of the acoustic cutoff associated with the basic frequency of the wave, which is likely in low-amplitude pulsators, the transmitted component might shock subsequently, heating the atmosphere and perhaps even producing a chromosphere.
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