Tibor Mitnyan

Aims. We are striving to better understand the stellar and orbital properties of compact and tight triple star systems with large dynamical interactions. Methods. We analyze TESS photometric data, radial velocity measurements, and eclipse timing variation curves for the triple star system, TIC 366240660, with a photodynamical code to infer the properties of all three stars and orbital motions. Results. With an outer orbital period of only 30.5 d, this is the second most compact triple reported in the literature. We have determined the masses and T _eff values of the three stars with an accuracy of about 1% and the radii to about 2%. The inclination angles of the two planes, and the mutual inclination angle are found with an accuracy of better than 1/3°. The system is determined to be quite flat (to within 1/2°), but with an outer eccentricity of e _out ≃ 0.33. We find that the properties of the secondary star of the inner binary are completely inconsistent with the evolution of a single star in isolation, and it must have transferred most of its envelope to the current primary star in the inner binary during a prior episode of mass transfer. The eclipse timing variation (ETV) curve derived from the TESS photometric data shows that, in addition to a typical dynamical delay curve at the period of the outer orbit, there is also a much larger amplitude anomalous sinusoidal-like delay with a period of 840 d. This latter feature in the ETV curve is not yet describable in simple analytic terms, but it appears certain that it can be explained by the near integer (≃13:1) ratio of the outer to the inner orbital periods. Conclusions. We have extensively explored the exotic and anomalous ETVs of this highly compact triple system and found that they can exceed hours for the inner binary eclipses, and several days for the outer orbital eclipses. We provide a preliminary explanation for how these are related to the 13:1 mean motion resonance of the outer to inner orbits.

Aims. Several hundred previously unknown 2+2 hierarchical doubly eclipsing quadruple stars have been identified in observations made with the space telescope TESS over the past eight years. Moreover, more than one hundred close hierarchical triple star systems have been identified in the same TESS datasets, each consisting of an inner eclipsing binary and a tertiary star that either eclipses the inner binary or is eclipsed by it. In this work we identify and photodynamically analyse the very first 2+2-type quadruple stellar system that is a member of both groups. TIC 433545934 consists of two eclipsing binaries that revolve around each other, forming a 2+2-type quadruple system in which, additionally, one binary eclipses the stars of the other binary. The TESS mission detected one such outer eclipse, which prompted particular interest in this system. Methods. Most of the data used in this study come from TESS observations, but we also obtained supplementary ground-based photometric measurements for this quadruple system. We combined the eclipse timing variation curves extracted from the TESS and ground-based follow-up data, the photometric light curves, and the spectral energy distribution in a complex photodynamical analysis to derive the stellar and orbital parameters of this dynamically interesting system. Results. The periods of the two inner eclipsing binaries are P _A = 2 ^d _. 07 and P _B = 1 ^d _. 41, while the mutual or outer period is P _AB = 224 ^d _. 5. The outer period alone makes this system the fifth most compact known 2+2-type quadruple. Moreover, what makes TIC 433545934 unique is that TESS observed a triple-dipped extra eclipsing event when the stars of binary B eclipsed the two components of binary A. We also identify similar extra eclipsing events in the archival, ground-based data of ASAS-SN and ATLAS. However, we find that these extra events occur only once during an outer revolution; that is, binary A does not eclipse the stars of binary B. This is consistent with our finding that the outer eccentricity is quite high, e _AB = 0.62. Our analysis reveals that binary A consists of two quite similar but slightly evolved late A-type stars ( q _A = 0.92), while in binary B, the primary star, whose mass lies between the masses of the two stars of binary A, is quite dominant, with q _B = 0.60. We find that the system is substantially flat, with mutual inclination angles below ≈2°.

In our previous analysis of the eclipse timing variation patterns of eclipsing binaries located in and near the Northern Continuous Viewing Zone (NCVZ) of the TESS space telescope, 135 hierarchical triple star candidates were found. Now, two additional years of TESS observations are available and, hence, we have extended the former analysis with the use of the new observational data. We now detect 168 triple star candidates in the updated and reanalyzed sample. The majority (∼74%) of them are identical to the former triples candidates. For many of them, our new solutions are more certain than the original ones. Therefore, we can now conclude that we have identified at least 66 short-period hierarchical triple stellar systems in the NCVZ with full confidence. In the case of the majority of the remaining systems in our sample, the presence of a close third stellar component appears to be very likely. We also identify additional, longer timescale period variations in 34 systems (20% of the total sample) and conclude that in at least three systems the presence of a fourth stellar component is quite plausible. Finally, we report the complete disappearance of the eclipses in two former EBs and detect eclipse depth variations in seven other EBs as well. We interpret this effect as the consequence of changing orbital inclination caused by a non-coplanar third body.

Hierarchical multiple stellar systems with short outer periods comprise an important subgroup of multiple star systems. In this paper we present the discovery and spectro-photodynamical analysis of the most compact known 3+1 quadruple stellar system, TIC 120362137. Through investigations of the observations made with the TESS satellite and ground-based follow up measurements, we find that the system consists of an eclipsing binary with a few-day-period that in turn eclipses, and is eclipsed by, a third star on a P _mid = 51.3 d orbit. This inner subsystem, which contains three stars that are more massive and hotter than the Sun, is more spatially compact than Mercury’s orbit around our Sun, and is orbited by a fourth Sun-like star with a period P _out = 1046 d. We detect the spectral lines of all four stars, making this system the most thoroughly studied 3+1 type quadruple stellar system. The future evolution of TIC 120362137 is also modeled, and we conclude that this entire system will likely end up as a pair of white dwarfs.

Aims. We have identified more than a hundred close triply eclipsing hierarchical triple star systems from data taken with the space telescope TESS. Many of them have outer periods less than, or close to, 100 days, and hence we call them ‘ultracompact hierarchical triples’. These systems are noteworthy in that we can potentially determine their dynamical and astrophysical parameters with a high precision, in many cases even without radial velocity data. In the present paper, we report the comprehensive study of ten new ultracompact triply eclipsing triple star systems, located in the northern ecliptic hemisphere, taken from this larger sample: TICs 198581208, 265274458, 283846096, 337993842, 351404069, 378270875, 403792414, 403916758, 405789362, and 461500036. Methods. Most of the data for this study come from TESS observations, but we obtained supplemental ground-based photometric measurements for two of the systems. The eclipse timing variation curves extracted from the TESS and the ground-based follow-up data, the photometric light curves, and the spectral energy distribution were combined in a complex photodynamical analysis to yield the stellar and orbital parameters of all ten systems. Results. The outer periods are in the range of 46.8–101.4 days. We found third-body-forced, rapid apsidal motion in four systems. Moreover, TIC 403916758 was found to be a double twin triple (i.e. both the inner and the outer mass ratios are close to unity). All of the systems are substantially flat, with mutual inclination angles of ≲5°. Finally, we have taken the results for the ten systems in the present paper and combined them with the system parameters for more than 30 other compact triples that we have reported on in previous work, in order to examine some of the global properties of these systems on a statistical basis.

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.

Context. Ultra-hot Jupiters (UHJs) orbiting pulsating A/F stars represent an important subset of the exoplanetary demographic. They are excellent candidates for the study of exoplanetary atmospheres, and are astrophysical laboratories for the investigation of planet-to- star interactions. Aims. We analysed the TESS light curve of the WASP-167 system, consisting of an F1V star and a substellar companion on a ~2.02 day orbit. Methods. We modelled the combination of the ellipsoidal variability and the Doppler beaming to measure the mass of WASP-167b, and the reflection effect to obtain constraints on the geometric albedo, while placing a special emphasis on noise separation. We implemented a basic model to determine the dayside (T_Day), nightside (T_Night), and intrinsic (T_Internal) temperatures of WASP-167b, and put a constraint on its Bond albedo. Results. We confirm the transit parameters of the planet seen in the literature. We find that a resonant ~2P⁻¹ stellar signal (which may originate from planet-to-star interactions) interferes with the phase curve analysis. After careful and thought-out treatment of this signal, we find M_p = 0.34 ± 0.22 M_J. We measure a dayside temperature of 2790 ± 100 K, classifying WASP-167b as an UHJ. We find a 2σ upper limit of 0.51 on its Bond albedo, and determine the geometric albedo at 0.34 ± 0.11 (1σ uncertainty). Conclusions. With an occultation depth of 106.8 ± 27.3 ppm in the TESS passband, the UHJ WASP-167b is an excellent target for atmospheric studies, especially those at thermal wavelength ranges, where the stellar pulsations are expected to be less influential.

Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics

Aims. We have identified nearly a hundred close triply eclipsing hierarchical triple star systems from data taken with the space telescope TESS. These systems are noteworthy in that we can potentially determine their dynamical and astrophysical parameters with a high precision. In the present paper, we report the comprehensive study of seven new compact triply eclipsing triple star systems taken from this larger sample: TICs 133771812, 176713425, 185615681, 287756035, 321978218, 323486857, and 650024463. Methods. Most of the data for this study come from TESS observations, but two of them have Gaia measurements of their outer orbits, and we obtained supplemental radial velocity (RV) measurements for three of the systems. The eclipse timing variation curves extracted from the TESS data, the photometric light curves, the RV points, and the spectral energy distribution (SED) are combined in a complex photodynamical analysis to yield the stellar and orbital parameters of all seven systems. Results. Four of the systems are quite compact with outer periods in the range of 41–56 days. All of the systems are substantially flat, with mutual inclination angles of ≲2°. Including the systems reported in this work, we have now studied in considerable detail some 30 triply eclipsing triples with TESS, and are accumulating a meaningful census of these systems.

Aims. We compiled a list of more than 3500 eclipsing binaries located in and near the northern continuous viewing zone (NCVZ) of the TESS space telescope that have sufficient TESS photometry to search for additional hidden components in these systems. In addition to discovering their hierarchical nature, we also determined their orbital parameters and analyzed their distributions. Methods. We obtained the TESS light curves of all targets in an automated way by applying convolution-aided differential photometry on the TESS full-frame images from all available sectors up to sector 60. Using a new self-developed Python GUI, we visually confirmed all of these light curves, determined the eclipsing periods of the objects, and calculated their eclipse-timing variations (ETVs). The ETV curves were used in order to search for nonlinear variations that could be attributed to a light travel-time effect (LTTE) or dynamical perturbations caused by additional components in these systems. We preselected 351 such candidates and modeled their ETVs with the analytic formulae of pure LTTE or with a combination of LTTE and dynamical perturbations. Results. We were able to fit a model solution for the ETVs of 135 hierarchical triple candidates, 10 systems of which were known from the literature, and the remaining 125 systems are new discoveries. These systems include some more noteworthy ones, such as five tight triples that are very close to their dynamical stability limit with a period ratio lower than 20, and three newly discovered triply eclipsing triples. We point out that dynamical perturbations occur in GZ Dra, which we found to be a triple, and that the system is one of the most strongly inclined systems known in the literature, with i_m = 58° ±7°. We also compared the distributions of some orbital parameters from our solutions with those from a previous Kepler sample. Finally, we verified the correlations between the available parameters for systems that have Gaia non-single star orbital solutions with those from our ETV solutions.