Indirect evidence for short period magnetic cycles in W UMa stars Period analysis of five overcontact systems

T. Borkovits, M. M. Elkhateeb, Sz Csizmadia, J. Nuspl, I. B. Bíró, T. Hegedüs, R. Csorvási

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Complex period variations of five W UMa type binaries (AB And, OO Aql, DK Cyg, V566 Oph, U Peg) were investigated by analyzing their O-C diagrams, and several common features were found. Four of the five systems show secular period variations at a constant rate on the order of |Ṗsec/P| ∼ 10-7 yr-1. In the case of AB And, OO Aql, and U Peg a high-amplitude, nearly one-century long quasi-sinusoidal pattern was also found. It might be explained as light-time effect, or by some magnetic phenomena, although the mathematical, and consequently the physical, parameters of these fits are very problematic, as the obtained periods are very close to the length of the total data range. The most interesting feature of the studied O-C diagrams is a low amplitude (∼2-4 × 10-3 d) modulation with a period around 18-20 yr in four of the five cases. This phenomenon might be indirect evidence of some magnetic cycle in late-type overcontact binaries as an analog to the observed activity cycles in RS CVn systems.

Original languageEnglish
Pages (from-to)1087-1097
Number of pages11
JournalAstronomy and Astrophysics
Volume441
Issue number3
DOIs
Publication statusPublished - Oct 2005

Keywords

  • Binaries: close
  • Binaries: eclipsing stars: activity
  • Stars: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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