Discovery of a double eclipsing binary with periods near a 3:2 ratio

TL;DR

This paper reports the discovery of a quadruple stellar system with two eclipsing binaries having orbital periods near a 3:2 ratio, suggesting possible Kozai cycles and tidal friction influence on their evolution.

Contribution

The study presents the first detailed light curve modeling of a quadruple system with two unresolved eclipsing binaries and provides a publicly available fitting code.

Findings

Orbital periods are within 0.1% of a 3:2 ratio.

One binary shows a significant eccentricity of about 0.18.

The system may be influenced by Kozai cycles and tidal friction (KCTF).

Abstract

The evolution of multiple stellar systems can be driven by Kozai cycles and tidal friction (KCTF), which shrink the orbit of the inner binary. There is an interesting possibility that two close binaries on a common long-period orbit experience mutually-induced KCTF. We present the discovery of a possible new quadruple system composed of two unresolved eclipsing binaries (EBs), CzeV343 (V~13.5 mag). We obtained photometric observations of CzeV343 that completely cover the two orbital periods and we successfully model the light curves as the sum of two detached EBs. We provide confidence intervals for the model parameters and minima timings by bootstrap resampling of our data. One of the EBs shows a distinctly eccentric orbit with a total eccentricity of about 0.18. The two orbital periods, 1.20937 and 0.80693 days, are within 0.1% of a 3:2 ratio. We speculate that this might be the result of KCTF-driven evolution of a quadruple system and we discuss this hypothesis in the context of other quadruple systems composed of two EBs. We make our double EB fitting code publicly available to provide a tool for long-term monitoring of the mutual orbit in such systems.