The architecture of the hierarchical triple star KOI 928 from eclipse timing variations seen in Kepler photometry

Abstract

We present a hierarchical triple star system (KIC 9140402) where a low-mass eclipsing binary orbits a more massive third star. The orbital period of the binary (4.98829d) is determined by the eclipse times seen in photometry from NASA's Kepler spacecraft. The periodically changing tidal field, due to the eccentric orbit of the binary about the tertiary, causes a change in the orbital period of the binary. The resulting eclipse timing variations provide insight into the dynamics and architecture of this system and allow the inference of the total mass of the binary (0.424 ± 0.017M⊙) and the orbital parameters of the binary about the central star. © 2011 Fermi Research Alliance, LLC. Monthly Notices of the Royal Astronomical Society © 2011 RAS.