English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We report on a study of eclipse timing variations in contact binary systems,using long-cadence lightcurves in the Kepler archive. As a first step,'observed minus calculated' (O-C) curves were produced for both the primary andsecondary eclipses of some 2000 Kepler binaries. We find ~390 short-periodbinaries with O-C curves that exhibit (i) random-walk like variations orquasi-periodicities, with typical amplitudes of +/- 200-300 seconds, and (ii)anticorrelations between the primary and secondary eclipse timing variations.We present a detailed analysis and results for 32 of these binaries withorbital periods in the range of 0.35 +/- 0.05 days. The anticorrelationsobserved in their O-C curves cannot be explained by a model involving masstransfer, which among other things requires implausibly high rates of ~0.01M_sun per year. We show that the anticorrelated behavior, the amplitude of theO-C delays, and the overall random-walk like behavior can be explained by thepresence of a starspot that is continuously visible around the orbit and slowlychanges 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 coefficientof the latitude dependence of the stellar differential rotation, of~0.003-0.013.

The Anticorrelated Nature of the Primary and Secondary Eclipse Timing Variations for the Kepler Contact Binaries