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 years, 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 8 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.
@article{arxiv.1502.01318,
title = {New RR Lyrae variables in binary systems},
author = {G. Hajdu and M. Catelan and J. Jurcsik and I. Dékány and A. J. Drake and J. -B. Marquette},
journal= {arXiv preprint arXiv:1502.01318},
year = {2015}
}