New compact hierarchical triple system candidates identified using Gaia DR3

Abstract

Aims. We introduce a novel way to identify new compact hierarchical triple stars by exploiting the huge potential of Gaia DR3 and also its future data releases. We aim to increase the current number of compact hierarchical triple systems significantly. Methods. We used several eclipsing binary catalogs from different sky surveys that list a total of more than 1 million targets to search for Gaia DR3 non-single-star orbital solutions with periods substantially longer than the eclipsing periods of the binaries. Those solutions in most cases are likely to belong to outer orbits of tertiary stars in those systems. We also attempted to validate some of our best-suited candidates using TESS eclipse timing variations. Results. We find 403 objects with suitable Gaia orbital solutions of which 27 are already known triple systems, leaving 376 newly identified hierarchical triple system candidates in our sample. We find the cumulative probability distribution of the outer orbit eccentricities to be very similar to those found in earlier studies based on observations of the Kepler and OGLE missions. We find measurable nonlinear eclipse timing variations or third-body eclipses in the TESS data for 192 objects which we also consider to be confirmed candidates. Of these, we construct analytical light-travel time effect models for the eclipse timing variations of 22 objects with wellsampled TESS observations. We compare the outer orbital parameters from our solutions with those from the Gaia solutions and find that the most reliable orbital parameter is the orbital period, while the values of the other parameters should be used with caution.