Light curve solutions and out-of-eclipse variabilities of six eccentric Kepler binaries

Abstract

As a result from light curve solutions of six eccentric Kepler binaries we determined their orbital elements and stellar parameters. We established linear dependence of their eccentricities on the orbital periods. Besides eclipses all targets reveal out-of-eclipse light variabilities modulated on different time scales. KIC 11409698, KIC 5284133 and KIC 8316503, the targets with the biggest eccentricities in our sample, exhibit tidally induced light brightening (hump) around the periastron phase. Just they reveal considerable reflection effect due to the big temperature difference of their components (above 2200 K). The detected humps confirmed the theoretical dependence of the hump amplitude on the eccentricity and mass ratio. KIC 12557713 and KIC 7691527 show photospheric activity caused by two diametrically opposite cool spots on the lateral sides of their primary components (flip-flop effect). We found flares in the Kepler data of KIC 7691527 that is another appearance of the activity of this target.