Hunt for extremely eccentric eclipsing binaries

¹ Astronomical Institute, Charles University, Faculty of Mathematics and Physics, V Holešovičkách 2, 180 00 Praha 8, Czech Republic
e-mail: zasche@sirrah.troja.mff.cuni.cz
² Variable Star and Exoplanet Section of the Czech Astronomical Society, Vsetínská 941/78, 757 01 Valašské Meziříčí, Czech Republic
³ FZU – Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, 182 21 Praha, Czech Republic

Received: 12 April 2021
Accepted: 6 June 2021

Abstract

We report the very first analysis of 27 eclipsing binary systems with high eccentricities that sometimes reach up to 0.8. The orbital periods for these systems range from 1.4 to 37 days, and the median of the sample is 10.3 days. Star CzeV3392 (= UCAC4 623 022784), for example, currently is the eclipsing system with the highest eccentricity (e = 0.22) of stars with a period shorter than 1.5 days. We analysed the light curves of all 27 systems and obtained the physical parameters of both components, such as relative radii, inclinations, or relative luminosities. The most important parameters appear to be the derived periods and eccentricities. They allow constructing the period–eccentricity diagram. This eccentricity distribution is used to study the tidal circularisation theories. Many systems have detected third-light contributions, which means that the Kozai-Lidov cycles might also be responsible for the high eccentricities in some of the binaries.