The anticorrelated nature of the primary and secondary eclipse timing variations for the kepler contact binaries

K. Tran, A. Levine, S. Rappaport, T. Borkovits, Sz Csizmadia, B. Kalomeni

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

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 MȮ yr-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.

Original languageEnglish
Article number81
JournalAstrophysical Journal
Volume774
Issue number1
DOIs
Publication statusPublished - Sep 1 2013

Fingerprint

eclipses
time measurement
curves
random walk
periodicity
mass transfer
starspots
timescale
longitude
periodic variations
orbits
orbitals
coefficients
analysis
rate

Keywords

  • binaries: eclipsing
  • binaries: general-stars: activity
  • stars: evolution
  • stars: rotation
  • starspots

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

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; Kalomeni, B.

In: Astrophysical Journal, Vol. 774, No. 1, 81, 01.09.2013.

Research output: Contribution to journalArticle

Tran, K. ; Levine, A. ; Rappaport, S. ; Borkovits, T. ; Csizmadia, Sz ; Kalomeni, B. / The anticorrelated nature of the primary and secondary eclipse timing variations for the kepler contact binaries. In: Astrophysical Journal. 2013 ; Vol. 774, No. 1.
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