A GRANULATION "FLICKER"-BASED MEASURE OF STELLAR SURFACE GRAVITY

In our previous work we found that high-quality light curves, such as those obtained by Kepler, may be used to measure stellar surface gravity via granulation-driven light curve "flicker" (F₈). Here, we update and extend the relation originally presented by Bastien et al. in 2013 after calibrating F₈ against a more robust set of asteroseismically derived surface gravities. We describe in detail how we extract the F₈ signal from the light curves, including how we treat phenomena, such as exoplanet transits and shot noise, that adversely affect the measurement of F₈. We examine the limitations of the technique, and, as a result, we now provide an updated treatment of the F₈-based log g error. We briefly highlight further applications of the technique, such as astrodensity profiling or its use in other types of stars with convective outer layers. We discuss potential uses in current and upcoming space-based photometric missions. Finally, we supply F₈-based log g values, and their uncertainties, for 27,628 Kepler stars not identified as hosts of transiting planets, with 4500 K < T_eff < 7150 K, 2.5 < log g < 4.6, K_p ≤ 13.5, and overall photometric amplitudes <10 parts per thousand.