A search for binary candidates among the fundamental mode RR Lyrae stars observed by Kepler

TL;DR

This study uses Kepler data to systematically search for binary companions among fundamental mode RR Lyrae stars by analyzing timing variations, aiming to increase known binary cases and improve mass measurements.

Contribution

It introduces a method to detect binarity in RR Lyrae stars through precise timing analysis of Kepler data, addressing the scarcity of known binary RR Lyrae systems.

Findings

No new binary RR Lyrae candidates identified

Demonstrates the effectiveness of timing analysis for binarity detection

Provides constraints on the binary fraction among RR Lyrae stars

Abstract

Although roughly half of all stars are considered to be part of binary or multiple systems, there are only two confirmed cases of RR Lyrae pulsators with companions. One of them is TU Uma (Wade et al 1999) - a classical RR Lyrae star in a very eccentric orbit - and the other is OGLE-BLG-RRLYR-02792 (Pietrzynski et al 2012). Considering the wealth of well-studied RR Lyrae stars, this number is astoundingly low. Having more RR Lyrae stars in binary systems at hand would be extremely valuable to get independent measurements of the masses. The data from the Kepler mission with their unprecedented precision and the long time span of about four years offer a unique possibility to systematically search for the signatures of binarity in RR Lyrae stars. Using the pulsation as a clock, we studied the variations in the timing of maximum light to hunt for possible binary systems in the sample.