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| Paper: |
Excitation mechanisms of oscillations in stars |
| Volume: |
40, Inside the Stars, IAU Colloquium 137 |
| Page: |
512 |
| Authors: |
Osaki, Yoji |
| Abstract: |
Excitation mechanisms of oscillations in stars are discussed, in particular on the problems of the Beta Cephei pulsations and of the solar oscillations. A long-standing mystery about the excitation mechanism of the Beta Cephei pulsations seems to have finally been solved, which is due to availability of the new 'OPAL' opacities. The very mechanism is the classical kappa-mechanism, however, due to enhanced heavy element opacities at temperature around 200,000 K. By using the new opacities, three independent groups have found pulsational instabilities for the fundamental radial mode and a few low-degree nonradial modes in Beta Cephei models. Stochastic excitation of solar oscillations by turbulent convection is then discussed. It is shown that the noise generation by quadrupole radiation concentrated at the top of the convection zone may well explain the frequency dependence of the observed solar acoustic power pumped into individual p-modes. |
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