Meredith L. Rawls edited More Discussion.tex  almost 9 years ago

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\subsection{Signatures of stellar activity}\label{actrot}  The double red giant eclipsing binary KIC 9246715 is an interesting system with photometric variations from stellar activity and a very eccentric orbit given its age, long orbital period, and well-separated nature. In this and the following section, we discuss how stellar activity and tidal forces have acted over the binary's lifetime to arrive at the system we see today.  As mentioned in Section \ref{segment}, the light curve residuals during one primary eclipse event show the presence of a star spot on Star 1 (see Figure \ref{fig:ELCresult}, lower right panel). This means at least Star 1 is magnetically active, and activity in the system is further supported by photometric variability of up to 2\% on a timescale approximately equal to half the orbital period \citep{gau14}. A magnetically active Star 1 is also consistent with Star 2 as the suspected oscillator, because strong magnetic fields may be responsible for damping solar-like oscillations.  Figures \ref{fig:emission1} and \ref{fig:emission2} investigate whether magnetic activity has any appreciable effect on absorption lines in either star. Following the approach of \citet{fro12}, we plot each target spectrum (colored line) on top of a model (dotted line), and show the difference below (solid black line). The model spectrum is a PHOENIX BT-Settl stellar atmosphere like the one described in Section \ref{bf} \citep{all03,asp09}, but now has a more representative $T_{\rm{eff}} = 5000$ and $\log g = 3.0$. It has also been convolved to a lower resolution much closer to that of the ARCES and TRES spectrographs.