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Title: THE ANTICORRELATED NATURE OF THE PRIMARY AND SECONDARY ECLIPSE TIMING VARIATIONS FOR THE KEPLER CONTACT BINARIES

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 {approx}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 {approx}0.01 M{sub Sun} yr{sup -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 {approx}50-200 days observed in the O - C curves suggest values for k, the coefficientmore » of the latitude dependence of the stellar differential rotation, of {approx}0.003-0.013.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. M.I.T. Department of Physics and Kavli Institute for Astrophysics and Space Research, 70 Vassar St., Cambridge, MA 02139 (United States)
  2. 37-575 M.I.T. Kavli Institute for Astrophysics and Space Research, 70 Vassar St., Cambridge, MA 02139 (United States)
  3. Baja Astronomical Observatory, H-6500 Baja, Szegedi ut, Kt. 766 (Hungary)
  4. Institute of Planetary Research, German Aerospace Center, Rutherfordstrasse 2, D-12489, Berlin (Germany)
  5. Department of Astronomy and Space Sciences, University of Ege, 35100 Bornova-Izmir (Turkey)
Publication Date:
OSTI Identifier:
22133933
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 774; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLITUDES; ECLIPSE; GRAPH THEORY; MASS TRANSFER; ORBITS; PERIODICITY; ROTATION; STARSPOTS; TIME DEPENDENCE