In this work, we report the discovery and analysis of six new compact triply eclipsing triple star systems found with the TESS mission: TICs 37743815, 42565581, 54060695, 178010808, 242132789, and 456194776. All of these exhibit distinct third-body eclipses where the inner eclipsing binary (EB) occults the third (‘tertiary’) star, or vice versa. We utilized the TESS photometry, archival photometric data, and available archival spectral energy distribution curves (SED) to solve for the properties of all three stars, as well as many of the orbital elements. We describe in detail our SED fits, search of the archival data for the outer orbital period, and the final global photodynamical analyses. From these analyses, we find that all six systems are coplanar to within 0°−5°, and are viewed nearly edge on (i.e. within a couple of degrees). The outer orbital periods and eccentricities of the six systems are {P_out (days), e}: {68.7, 0.36}, {123, 0.16}, {60.7, 0.01}, {69.0, 0.29}, {41.5, 0.01}, {93.9, 0.29}, respectively, in the order the sources are listed above. The masses of all 12 EB stars were in the range of 0.7–1.8 M_⊙ and were situated near the main sequence. By contrast, the masses and radii of the tertiary stars ranged from 1.5 to 2.3 M_⊙ and 2.9 to 12 R_⊙, respectively. We use this information to estimate the occurrence rate of compact flat triple systems..

In this work we report the discovery and analysis of three new triply eclipsing triple star systems found with the TESS mission during its observations of the northern skies: TICs 193993801, 388459317, and 52041148. We utilized the TESS precision photometry of the binary eclipses and third-body eclipsing events, ground-based archival and follow-up photometric data, eclipse timing variations, archival spectral energy distributions, as well as theoretical evolution tracks in a joint photodynamical analysis to deduce the system masses and orbital parameters of both the inner and outer orbits. In one case (TIC 193993801) we also obtained radial velocity measurements of all three stars. This enabled us to ‘calibrate’ our analysis approach with and without ‘truth’ (i.e. RV) data. We find that the masses are good to 1–3 per cent accuracy with RV data and 3–10 per cent without the use of RV data. In all three systems we were able to find the outer orbital period before doing any detailed analysis by searching for a longer-term periodicity in the ASAS-SN archival photometry data – just a few thousand ASAS-SN points enabled us to find the outer periods of 49.28 d, 89.86 d, and 177.0 d, respectively. From our full photodynamical analysis we find that all three systems are coplanar to within 1°−3°. The outer eccentricities of the three systems are 0.003, 0.10, and 0.62, respectively (i.e. spanning a factor of 200). The masses of the three stars {Aa, Ab, and B} in the three systems are: {1.31, 1.19, 1.34}, {1.82, 1.73, 2.19}, and {1.62, 1.48, 2.74} M_⊙, respectively.

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.

We report the discovery of a compact triply eclipsing triple star system in the southern continuous viewing zone of the TESS space telescope. TIC 278825952 is a previously known, but unstudied circular eclipsing binary with a period of 4.781 d with a tertiary component in a wider, circular orbit of 235.55-d period that was found from three sets of third-body eclipses and from light travel-time effect dominated eclipse timing variations. We performed a joint photodynamical analysis of the eclipse timing variation curves, photometric data, and the spectral energy distribution, coupled with the use of PARSEC stellar isochrones. We find that the inner binary consists of slightly evolved, near twin stars of masses of 1.12 and 1.09 M_⊙ and radii of 1.40 and 1.31 R_⊙. The third, less massive star has a mass of 0.75 M_⊙ and radius of 0.70 R_⊙. The low mutual inclination and eccentricities of the orbits show that the system is highly coplanar and surprisingly circular.

In this work we report the independent discovery and analysis of nine new compact triply eclipsing triple star systems found with the TESS mission: TICs 47151245, 81525800, 99013269, 229785001, 276162169, 280883908, 294803663, 332521671, and 356324779. Each of these nine systems exhibits distinct third-body eclipses where the third (‘tertiary’) star occults the inner eclipsing binary (EB), or vice versa. We utilize a photodynamical analysis of the TESS photometry, archival photometric data, TESS eclipse timing variations of the EBs, available archival spectral energy distribution curves (SED), and, in some cases, newly acquired radial velocity observations, to solve for the parameters of all three stars, as well as most of the orbital elements. From these analyses we find that the outer orbits of all nine systems are viewed nearly edge on (i.e., within ≲ 4^○), and 6 of the systems are coplanar to within 5^○; the others have mutual inclination angles of 20^○, 41^○, and possibly 179^○ (i.e., a retrograde outer orbit). The outer orbital periods range from 47.8 days to 604 days, with eccentricities spanning 0.004 to 0.61. The masses of all 18 EB stars are in the range of 0.9–2.6 M_⊙ and are mostly situated near the main sequence. By contrast, the masses and radii of the tertiary stars range from 1.4–2.8 M_⊙ and 1.5–13 R_⊙, respectively. We make use of the system parameters from these 9 systems, plus those from a comparable number of compact triply eclipsing triples published previously, to gain some statistical insight into their properties.

Context. A former analysis of eclipse timing variation (ETV) curves of eclipsing binaries (EBs) observed by the Kepler spacecraft during its ∼4-year-long prime mission has led to the discovery and characterization of 221 hierarchical triple star system with different confidence levels. Although the prime Kepler mission ended in 2013 (a little more than a decade ago), the TESS space telescope has revisited the original Kepler field on several occasions in between 2019 and 2024, thereby extending the time base of high-precision eclipse timing observations for a substantially longer interval. Aims. In this paper, we re-analyse the extended ETV curves of the formerly identified triple star candidates and many other Kepler EBs. Besides the confirmations of the former findings and/or the improvements of the triple systems’ orbital properties, the extended time base allows us to identify several new, longer outer period triple systems, and it also makes a more detailed study of the dynamical perturbations in the tightest triple stars possible. Methods. We extend the ETV curves of the Kepler triples with those mid-eclipse times that can be deduced from the TESS observations and, moreover, from targeted ground-based follow-up observations for a number of the objects. In general, we used the same methods that were applied for the older studies, which are described in the literature. Due to the lower quality of the TESS observations, however, for the fainter systems we averaged light curves of the EBs for 5–20 consecutive cycles, and thereby calculated ‘normal’ minima from these averaged light curves. Results. In conclusion, we identified 243 hierarchical triple star candidates in the Kepler sample. This sample strongly overlaps our former, nine-year-old sample, confirming the older results, or providing new solutions for 193 systems of the 2016 sample. For the remaining 28 hierarchical triple candidates of that former study, we have been unable to find new solutions, either because of the disappearance of the eclipses due to orbital plane precession, or due to instrumental reasons. On the other hand, due to the extended time series, we have been able to identify 50 new, longer-period triple star candidates as well. We briefly discuss the main properties of each individual system and present statistical studies of the results.