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 well-sampled 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.

Mass Ratio Distribution of Hierarchical Triple Systems from the LAMOST-MRS Survey

“…This suggests that our previous hypothesis is reasonable. Recently, Czavalinga et al (2023) summarized the inner and outer periods of some discovered triple systems and found that most of the inner binary periods are less than 10 days, while most of the outer periods are larger than 300 days, which further confirms the validity of our hypothesis for most triple systems.…”

“…Using the Hipparcos catalog, Eggleton and Tokovinin found that at least 10% of bright stars belong to triple-star (or multiple-star) systems (Eggleton & Tokovinin 2008. Czavalinga et al (2023) found 376 newly compact hierarchical triple (CHT) system candidates in their study. They considered that the orbital period is the most trustworthy orbital parameter and that other parameters should be used cautiously.…”

“…The hierarchical triple-star system consists of three components that are organized into an inner binary pair and a more distant outer star (Czavalinga et al 2023). To facilitate the application of Kepler's law, we can approximate the triple as a large orbit (considering the inner binary as a whole and the third star as an outer binary) over a small orbit.…”

Seven new triply eclipsing triple star systems

“…22 we present a set of four correlation plots among some of the physically interesting parameters associated with our collection of 33 recently analyzed triply eclipsing triples. To the seven sources presented in this work, we have added the 15 triples from our previous closely related papers (Rappaport et al 2022(Rappaport et al , 2023, as well as eleven triples studied in Borkovits et al (2019aBorkovits et al ( , 2020bBorkovits et al ( , 2022a, Czavalinga et al (2023b), andMitnyan et al (2020) using largely the same selection criteria and methods of analysis.…”