The influence of space- and time-dependent random mass density field, associated with granules, on frequencies and amplitudes of the solar p-modes is examined in the limit of weak random fields and small amplitude oscillations. The p-modes are approximated by the sound waves which propagate in the gravity-free medium. Using a perturbative method, we derive a dispersion relation which is solved for the case of wave noise for which the spectrum E(k, w) similar to E(k)delta(w - c(r)k), where delta is the Dirac's delta-function and c(r) is the random phase speed. We find that at c(r) = w/k a resonance occurs at which the cyclic frequency w tends to infinity. For values of c(r) which are close to the resonance point, the frequency shift may be both negative or positive and the imaginary part of the frequency attains the negative (positive) sign for c(r) < w/k(c(r) > w/k).
Influence of wave noise on frequencies and amplitudes of the solar p-modes
NOCERA L;
2002
Abstract
The influence of space- and time-dependent random mass density field, associated with granules, on frequencies and amplitudes of the solar p-modes is examined in the limit of weak random fields and small amplitude oscillations. The p-modes are approximated by the sound waves which propagate in the gravity-free medium. Using a perturbative method, we derive a dispersion relation which is solved for the case of wave noise for which the spectrum E(k, w) similar to E(k)delta(w - c(r)k), where delta is the Dirac's delta-function and c(r) is the random phase speed. We find that at c(r) = w/k a resonance occurs at which the cyclic frequency w tends to infinity. For values of c(r) which are close to the resonance point, the frequency shift may be both negative or positive and the imaginary part of the frequency attains the negative (positive) sign for c(r) < w/k(c(r) > w/k).File | Dimensione | Formato | |
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Descrizione: Influence of wave noise on frequencies and amplitudes of the solar p-modes
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