Candidates for RR~Lyrae in binary systems from the OGLE Galactic bulge survey. (arXiv:1905.11878v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Prudil_Z/0/1/0/all/0/1">Z. Prudil</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Skarka_M/0/1/0/all/0/1">M. Skarka</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liska_J/0/1/0/all/0/1">J. Li&#x161;ka</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Grebel_E/0/1/0/all/0/1">E. K. Grebel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_C/0/1/0/all/0/1">C.-U. Lee</a>

We present 20 newly discovered candidates for binary systems with an RR~Lyrae
companion. Using the photometric data from the Optical Gravitational Lensing
Experiment (OGLE) and Korea Microlensing Telescope Network (KMTNet) for the
Galactic bulge, we searched for binary candidates among non-modulated
fundamental-mode RR~Lyrae variables. We constructed and investigated over 9000
$O-C$ diagrams for individual pulsators, in order to find signs of the
light-travel time effect. We found 20 variables exhibiting cyclic variation in
the $O-C$ (time of the observed minus calculated brightness maximum) diagram,
which can be associated with a second component in the system, but for
confirmation of binarity, a long-term radial velocity study is necessary. The
modeling of the $O-C$ diagrams yields orbital parameters, estimates of the
semi-amplitude of the radial velocity curve, and the mass function. The orbital
periods of our candidates range from 3 to 15 years. Two of the binary
candidates display a minimum mass higher than the assumed mass of the RR~Lyrae
component, which points towards an evolved companion that can under some
circumstances contribute significantly to the total light of the system.

We present 20 newly discovered candidates for binary systems with an RR~Lyrae
companion. Using the photometric data from the Optical Gravitational Lensing
Experiment (OGLE) and Korea Microlensing Telescope Network (KMTNet) for the
Galactic bulge, we searched for binary candidates among non-modulated
fundamental-mode RR~Lyrae variables. We constructed and investigated over 9000
$O-C$ diagrams for individual pulsators, in order to find signs of the
light-travel time effect. We found 20 variables exhibiting cyclic variation in
the $O-C$ (time of the observed minus calculated brightness maximum) diagram,
which can be associated with a second component in the system, but for
confirmation of binarity, a long-term radial velocity study is necessary. The
modeling of the $O-C$ diagrams yields orbital parameters, estimates of the
semi-amplitude of the radial velocity curve, and the mass function. The orbital
periods of our candidates range from 3 to 15 years. Two of the binary
candidates display a minimum mass higher than the assumed mass of the RR~Lyrae
component, which points towards an evolved companion that can under some
circumstances contribute significantly to the total light of the system.

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