Matteo Cantiello edited Mode Visibility.tex  about 9 years ago

Commit id: d3151cc8ca6b9f7683227219f935a4eaa1067430

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%by the magnetic greenhouse effect   and the observations of \cite{Mosser_2011} is shown in Fig.~\ref{fig:moneyplot}. The agreement is striking, and holds over a large baseline in $\nu_{\rm max}$. The predicted visibility of equation \ref{eqn:vis} has no free parameters, although there is some uncertainty in the value of $\tau_0$. Additional scatter can be accounted for by a range of stellar masses, metallicities, and inclinations in the the observed sample.  This seems to demonstrates that the cores of stars with weaker dipole modes host a mechanism able to efficiently trap waves tunneling through the evanescent region. This is further supported by smaller degree of suppression observed in $\ell=2$ modes, for which the transmission coefficient $T$ is smaller.  There are two additional consequences for mode visibility. First, the larger effective damping rate for suppressed modes will lead to larger line widths in the oscillation power spectrum. The linewidth of a non-suppressed mode is the mode damping rate $\gamma_{\alpha}$, which in general is not equal to $\tau_{0}^{-1}$ because non-radial mixed modes have some inertia in the core (in contrast to radial modes which are confined to the envelope). The linewidth of a suppressed mode is $\tau_{0}^{-1} + \Delta \nu T^2_{\ell}$ and is generally much larger. The suppressed modes in KIC 8561221 (\cite{Garcia_2014}) indeed have much larger linewidths.  The second consequence is that, under the assumption that none of the energy tunneling through the evanescent region makes it back to the envelope, {\it only} envelope modes (p modes) will be visible in the suppressed part of the oscillation spectrum. Mixed modes in the usual sense no longer exist. % because of the strong magnetic field in the g mode cavity. % Although magneto-gravity modes may still exist, their high $\ell$ nature in the core makes them unlikely to be observed at the surface of the star (i.e., they have very large mode inertias).