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The Kepler light curve of DF Cyg is unparalleled in precision and cadence forany RV Tau star to date spanning a baseline of $\sim$4 years and clearlydisplaying the signature pulsating behavior of alternating deep and shallowminima as well as the long-term trend indicative of an RVb-type variable. Wemeasured DF Cyg's formal period (the time interval between two successive deepminima) to be $~49.84 \pm 0.02~$days. The trend in the arrival times emulatesthat of the long-term period. There appears to be precisely 16 deep+shallowminima cycles in one long-term cycle, suggesting a long-term cycle period of$\approx$ $795 \pm 5~$days. We argue that binarity may naturally explain thelong-term periodicity in DF Cyg. The spectral energy distribution of DF Cygfeatures an infrared excess indicative of a disk possibly linked to a binarycompanion. From a recent Gaia parallax measurement for DF Cyg, we calculatedthat it has a distance of $990 \pm 372$pc and a physical radius of $R_\star =10.3 \pm 3.8$ R$_\odot$. From kinematics and geometric arguments, we argue thatthe most likely interpretation for the decrease in flux from the long-periodmaximum to the long-period minimum, as well as the reduction of short-termpulsation amplitude, is caused by an occulting body such as a disk surroundingDF Cyg and its binary companion.

Evidence for Binarity and Possible Disk Obscuration in Kepler Observations of the Pulsating RV Tau Variable DF Cygni