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Formation and evolution of W Ursa Majoris stars: fallacies and corrections

Authors

  • Z. Eker,

    Corresponding author
    1. TÜBİTAK National Observatory, Akdeniz University Campus, 07058 Antalya, Turkey
    2. Çanakkale Onsekiz Mart University, Faculty of Sciences and Arts, Ulupınar Astrophysical Observatory, 17100 Çanakkale, Turkey
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  • O. Demircan,

    1. Çanakkale Onsekiz Mart University, Faculty of Sciences and Arts, Ulupınar Astrophysical Observatory, 17100 Çanakkale, Turkey
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  • S. Bilir

    1. Istanbul University, Science Faculty, Department of Astronomy and Space Sciences, 34119 Istanbul, Turkey
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E-mail: eker@comu.edu.tr

ABSTRACT

Period histograms of eclipsing binaries generated with data from the All-Sky Automated Survey cannot be interpreted only using orbital evolution. Eclipse probabilities, selection effects and space distributions in the solar neighbourhood should be considered before any interpretations are made. Depending upon the physical dimensions (the total mass and the period) of the progenitor stars and the efficiency of the angular momentum loss mechanism, a newly formed W Ursa Majoris type binary can be at any age up to several Gyr. Also, the evolution in the contact stage is controlled not only by angular momentum and mass loss but also by mass transfer between the component stars. Thus, the mean life of the contact stages should be about 1.6 Gyr. A different time-scale would cause inconsistencies.

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