patrick gaulme edited Discussion.tex  over 8 years ago

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These relations should be valid only for oscillation modes of large radial order $n$, where pressure modes can be mathematically described in the frame of the ``asymptotic development'' \citep{tas80}. Even though red giants do not perfectly match these conditions, because the observed oscillation modes have radial orders $n < 10$, the scaling relations do appear to work. Quantifying how well they work and in what conditions is more challenging. This is why measuring oscillating stars' masses and radii independently from seismology is so important.  Surprisingly, when \citet{gau13} and \citet{gau14} analyzed the oscillation modes of KIC 9246715 to estimate global asteroseismic parameters, only one set of modes was found. Of the 17 oscillating RG/EBs in the \emph{Kepler} field, KIC 9246715 is the only one with a pair of giant stars (the rest are composed of a giant star and a main sequence star). The oscillation spectrum as well as its representation as an \'echelle diagram are shown in Figures \ref{fig:seismo} and \ref{fig:echelle}. Assuming a single oscillating star, the mode amplitudes are quite low ($A_{\rm{max}}(l=0) \simeq 14$ ppm, and not 6.6 ppm as erroneously reported by \citealt{gau14}) compared to the 20 ppm we expect based on mode amplitude scaling relations \citep{cor13}. In addition, the light curve displays photometric variability as large as 2\% peak-to-peak, which is typical of the signal created by spots on stellar surfaces. The pseudo-period of this variability was observed to be about half the orbital period, which suggests resonances in the system. \citet{gau14} speculated that star spots may be responsible for inhibiting oscillations on the smaller star, and a similar behavior was observed in other RG/EB systems. {\textbf{In this paper, we reestimate the global seismic parameters of the oscillation spectrum that was previously identified (Sect. \ref{subsubsec_main_osc}), and we report the marginal detection of the second set of oscillations oscillations, where only a proxy of $\Delta\nu$ can be measured  (Sect. \ref{subsubsec_second_osc}).} \subsubsection{Global asteroseismic parameters of main oscillator}  \label{subsubsec_main_osc}