Nonlinear δ Scuti models: The main sequence catastrophe?
For nonlinear models of 0.4 M⊙ and 2.0 M⊙ δ Scuti stars, pulsation amplitudes obtained in this region depend critically upon artificial viscosity parameters. Models with limited viscosity attain huge amplitudes. Furthermore, it is found that nonlinear stability properties depend primarily upon the amplitude. Determination of the actual dissipation mechanism is thus crucial to our understanding of these objects, and probably other main sequence pulsators as well. At present the most likely mechanisms appear to be 1) dissipation in the atmosphere, corona and wind; 2) turbulent dissipation in the convective zones; 3) magnetic fields.
KeywordsConvective Zone Globular Cluster Turbulent Dissipation Viscosity Parameter Limited Viscosity
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