THE ANTICORRELATED NATURE OF THE PRIMARY AND SECONDARY ECLIPSE TIMING VARIATIONS FOR THE KEPLER CONTACT BINARIES
Author(s)Borkovits, T.; Csizmadia, Sz.; Kalomeni, B.; Tran, Ky-Anh; Levine, Alan M; Rappaport, Saul A; ... Show more Show less
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We report a study of the eclipse timing variations in contact binary systems, using long-cadence lightcurves from the Kepler archive. As a first step, observed minus calculated (O – C) curves were produced for both the primary and secondary eclipses of some 2000 Kepler binaries. We find ~390 short-period binaries with O – C curves that exhibit (1) random walk-like variations or quasi-periodicities, with typical amplitudes of ±200-300 s, and (2) anticorrelations between the primary and secondary eclipse timing variations. We present a detailed analysis and results for 32 of these binaries with orbital periods in the range of 0.35 ± 0.05 days. The anticorrelations observed in their O – C curves cannot be explained by a model involving mass transfer, which, among other things, requires implausibly high rates of ~0.01 M[subscript ☉] yr[superscript –1]. We show that the anticorrelated behavior, the amplitude of the O – C delays, and the overall random walk-like behavior can be explained by the presence of a starspot that is continuously visible around the orbit and slowly changes its longitude on timescales of weeks to months. The quasi-periods of ~50-200 days observed in the O – C curves suggest values for k, the coefficient of the latitude dependence of the stellar differential rotation, of ~0.003–0.013.
DepartmentMassachusetts Institute of Technology. Department of Physics; MIT Kavli Institute for Astrophysics and Space Research
Tran, K., A. Levine, S. Rappaport, T. Borkovits, Sz. Csizmadia, and B. Kalomeni. “ THE ANTICORRELATED NATURE OF THE PRIMARY AND SECONDARY ECLIPSE TIMING VARIATIONS FOR THE KEPLER CONTACT BINARIES .” The Astrophysical Journal 774, no. 1 (August 19, 2013): 81. © 2013 The American Astronomical Society
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