New RR Lyrae variables in binary systems.

G. Hajdu , M. Catelan , J. Jurcsik , I. Dekany , A. J. Drake , J. -B. Marquette (1)

1 IAP - Institut d'Astrophysique de Paris

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.

Mots clés: methods: data analysis; techniques: photometric; binaries: general; stars: fundamental parameters; stars: oscillations; stars: variables: RR Lyrae; Astrophysics - Solar and Stellar Astrophysics; Astrophysics - Instrumentation and Methods for Astrophysics

Domaines: Planète et Univers [physics]; Astrophysique [astro-ph]

G. Hajdu, M. Catelan, J. Jurcsik, I. Dekany, A. J. Drake, et al.. New RR Lyrae variables in binary systems.. Mon. Not. R. Astron. Soc., 2015, 449, pp.L113-L117. ⟨10.1093/mnrasl/slv024⟩. ⟨insu-03644972⟩