Limits on Mode Coherence Due to a Non-static Convection Zone. (arXiv:1902.05615v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Montgomery_M/0/1/0/all/0/1">M. H. Montgomery</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hermes_J/0/1/0/all/0/1">J. J. Hermes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Winget_D/0/1/0/all/0/1">D. E. Winget</a>

The standard theory of pulsations deals with the frequencies and growth rates
of infinitesimal perturbations in a stellar model. Modes which are calculated
to be linearly driven should increase their amplitudes exponentially with time;
the fact that nearly constant amplitudes are usually observed is evidence that
nonlinear mechanisms inhibit the growth of finite amplitude pulsations. Models
predict that the mass of DAV convection zones is very sensitive to temperature
(i.e., $M_{text{CZ}} propto T_{text{eff}}^{-90}$) leading to the possibility
that even “small amplitude” pulsators may experience significant nonlinear
effects. In particular, the outer turning point of finite-amplitude g-mode
pulsations can vary with the local surface temperature, producing a reflected
wave that is slightly out of phase with that required for a standing wave. This
can lead to a lack of coherence of the mode and a reduction in its global
amplitude. We compute the size of this effect for specific examples and discuss
the results in the context of Kepler and K2 observations.

The standard theory of pulsations deals with the frequencies and growth rates
of infinitesimal perturbations in a stellar model. Modes which are calculated
to be linearly driven should increase their amplitudes exponentially with time;
the fact that nearly constant amplitudes are usually observed is evidence that
nonlinear mechanisms inhibit the growth of finite amplitude pulsations. Models
predict that the mass of DAV convection zones is very sensitive to temperature
(i.e., $M_{text{CZ}} propto T_{text{eff}}^{-90}$) leading to the possibility
that even “small amplitude” pulsators may experience significant nonlinear
effects. In particular, the outer turning point of finite-amplitude g-mode
pulsations can vary with the local surface temperature, producing a reflected
wave that is slightly out of phase with that required for a standing wave. This
can lead to a lack of coherence of the mode and a reduction in its global
amplitude. We compute the size of this effect for specific examples and discuss
the results in the context of Kepler and K2 observations.

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