Jim Fuller edited Mode Visibility.tex  almost 9 years ago

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\section{Mode Visibility}  Solar-like oscillations are driven by stochastic energy input near the outer surface of the convective envelope. from turbulent near-surface convection.  At its time-averaged equilibrium amplitude, the energy input and damping rates of the mode are equal \cite{Dupret_2009}. %Modes suppressed via the magnetic greenhouse effect have an extra source of damping determined by the rate at which energy leaks through the evanescent region separating the acoustic cavity from the g-mode cavity.   Waves with angular frequency $\omega \sim \omega_{\rm max} = 2 \pi \nu_{\rm max}$ are excited via convective motions, the waves propagate downward as acoustic waves until their frequency is less than the local Lamb frequency for waves of angular degree $\ell$, i.e., until $\omega = L_l = \sqrt{l(l+1)} c_s/r$, where $c_s$ is the sound speed and $r$ is the radial coordinate. At this boundary, part of the wave flux is reflected, and part of it tunnels through. The wave resumes propagating inward as a gravity wave in the radiative core where $\omega < N$, with $N$ the Brunt-Vaisala frequency.