New RR Lyrae variables in binary systems

Hajdu, Gergely and Catelan, M. and Jurcsik, Johanna and Dékány, István and Drake, A. J. (2015) New RR Lyrae variables in binary systems. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS, 449 (1). L113-L117. ISSN 1745-3925

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Abstract

Despite their importance, very few RR Lyrae (RRL) stars have been known to reside in binary systems. We report on a search for binary RRL in the OGLE-III Galactic bulge data. Our approach consists in the search for evidence of the light-travel time effect in so-called observed minus calculated (O-C) diagrams. Analysis of 1952 well-observed fundamental-mode RRL in the OGLE-III data revealed an initial sample of 29 candidates. We used the recently released OGLE-IV data to extend the baselines up to 17 yr, leading to a final sample of 12 firm binary candidates. We provide O-C diagrams and binary parameters for this final sample, and also discuss the properties of eight additional candidate binaries whose parameters cannot be firmly determined at present. We also estimate that ≳ 4 per cent of the RRL reside in binary systems.

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