Astrophys. J., 774, 81 (2013/September-1)
The anticorrelated nature of the primary and secondary eclipse timing variations for the Kepler contact binaries.
TRAN K., LEVINE A., RAPPAPORT S., BORKOVITS T., CSIZMADIA Sz. and KALOMENI B.
Abstract (from CDS):
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_☉/yr. 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.
binaries: eclipsing - binaries: general - stars: activity - stars: evolution - starspots - stars: rotation
View the reference in ADS
To bookmark this query, right click on this link: simbad:2013ApJ...774...81T and select 'bookmark this link' or equivalent in the popup menu