Meredith L. Rawls edited More Discussion.tex  over 8 years ago

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\subsection{Signatures of stellar activity}\label{actrot}  KIC 9246715 is an interesting pair of well-separated red giants that exhibit photometric variations from stellar activity, weak or absent solar-like oscillations, and a notably eccentric orbit. 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. \revise{The first confirmed case of activity and/or tides suppressing convection-driven oscillations was \citet{der11}, and as \citet{gau14} showed, stellar activity and tides likely play an important role in many RG/EBs.}  \revise{In this system, the light curve residuals discussed in Section \ref{segment} and Figure \ref{fig:ELCresult} show significant scatter during both eclipses, and especially primary eclipse (when Star 1 is in front).} 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 main oscillator, because strong magnetic fields may be responsible for damping solar-like oscillations. oscillations, \newrevise{as described in \citet{ful15}}.  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 (solid 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}, with $T_{\rm{eff}} = 5000$ and $\log g = 3.0$. It has been convolved to a lower resolution much closer to that of the ARCES and TRES spectrographs.