Khalid Barkaoui

Planetary transits require a fortuitous alignment between a planet’s orbit and our line of sight, but dynamical interactions can render this geometric coincidence only temporary. We report the discovery of the hot Jupiter TOI-2535b, the first confirmed planet orbiting a single star whose transits have been directly observed to disappear. Over 7 yr of photometry from NASA’s Transiting Exoplanet Survey Satellite (TESS), the planet’s transit chord traversed and eventually moved off the stellar disk entirely, with an impact parameter changing at the rate of b ̇ = 0.16 yr − 1 . The transit midtimes also show significant departures of ±6 hr from a linear ephemeris. Joint modeling of the transit timing and duration variations (TTVs and TDVs) and NEID radial-velocity data indicates the presence of a nearby, mutually inclined ( i _mut ≳ 5 ^∘ ) planetary perturber, with the TDV being primarily due to precession of the planets’ orbital planes. Our dynamical modeling reveals that the perturber is likely of Saturn-mass or greater and in a mean-motion resonance with TOI-2535b, making this an unusual system that contains two short-period giant planets. The TDVs measured for TOI-2535b represent one of the most extreme examples of planet–planet interactions driving orbital evolution on human timescales.

We report the discovery of two planets, a hot Jupiter (HJ) and a nearby outer sub-Neptune, orbiting the star TOI-4468. This system is unique among the current exoplanet census in that it features a close outer companion to a HJ without an accompanying inner companion. By jointly fitting radial velocity (RV) measurements taken with the NEID spectrograph and transit photometry from the Transiting Exoplanet Survey Satellite (TESS) and several ground-based observatories, we constrain the orbital periods, masses, and radii of these two planets. We confirm the planetary nature of the HJ TOI-4468 b ( R = 1.01 R _J , m = 0.54 M _J , P = 2.77 days). We also validate the outer planet TOI-4468 c ( R = 0.28 R _J , P = 7.01 days) statistically, incorporating constraints from ground-based observations. We also identify, but cannot confirm, an additional RV signal that may be due to an outer giant in this system with an orbital period of 624 days. From the observed geometry of this system, we argue that it must never have encountered an early secular resonance that is thought to excite the mutual inclination of other HJ/outer companion systems. We discuss the possibility of an undetected inner companion, as well as potential implications for HJ formation.

Context. Gas giant planets with orbital periods of P ∼8–200 d, known as warm Jupiters, are thought to be largely unaffected by the tidal interactions that can often erase valuable information on the dynamical histories of hot Jupiters. Their orbital eccentricities ( e ) and stellar obliquities are therefore expected to be preserved, making them valuable probes of giant-planet formation and migration. Aims. Our aim is to identify and characterise transiting warm Jupiters and expand the sample of well-characterised systems and enable further studies of giant-planet formation and migration. Methods. We analysed TESS transit photometry, together with ground-based radial velocity (RV) measurements. We performed a joint fit of the photometric and spectroscopic data from the TS23 and FIES spectrographs to determine the planetary and orbital parameters. Results. We report on the discovery and characterisation of two new, transiting warm Jupiters; TOI-5120 b ( M _p = 1.23 ± 0.05 M _J , R _p = 0.969 ± 0.017 R _J , P = 24.91645 ± 0.00002 d, e = 0.10 ± 0.02) and TOI-5699 b ( M _p = 0.25 ± 0.03 M _J , R _p = 0.996 ± 0.015 R _J , P = 22.01850 ± 0.00004 d, e = 0.30 _−0.08 ^+0.09 ). We also refined the parameters of the known warm Jupiter TOI-2158 b ( M _p = 0.87 ± 0.04 M _J , R = 0.899 ± 0.015 R _J , P = 8.60079 _−0.00001 ^+0.00002 d, e = 0.028 _−0.014 ^+0.013 ). In addition, we detected an outer planetary companion, TOI-2158 c ( M _p sin i = 1.62 ± 0.13 M _J , P = 414.5 _−1.6 ^+1.5 d, e = 0.54 ± 0.04), and identified a long-term RV trend that could indicate another planetary companion on a wide orbit. Conclusions. The diverse architectures of these systems, particularly the presence and absence of outer companions, highlight the range of dynamical pathways leading to warm Jupiters.

High-resolution imaging is widely used to constrain false positive scenarios in exoplanet validation, but it is a finite follow-up resource that reaches only a subset of candidates, and its population-level impact on validation outcomes has not been quantified through controlled removal experiments. Using an automated pipeline built on TRICERATOPS , we compute the false positive probability (FPP) of 443 TESS planet candidates. For the 264 planet candidates with high-resolution imaging observations, we compute FPP with and without the corresponding contrast curves, allowing us to quantify the impact of the additional data. We find that 72% of 68 contrast-curve-bearing validated planets would fail validation without their adopted contrast curves. The fraction requiring imaging decreases with increasing planet size, from 100% below 1.7 R _⊕ to 33% above 4 R _⊕ : within our sample and TRICERATOPS -based analysis, the availability of high-resolution imaging directly limits the yield of small-planet validation and the supply of validated targets for atmospheric characterization. Our analysis statistically validates 64 new TESS planets with sizes spanning 0.94 to 7.83 R _⊕ across hosts of spectral types: M through F. Four of these are highly amenable to JWST observations based on the transmission and emission spectroscopy metrics, and each achieves validation only with its imaging constraint.

Short-period white-dwarf–main-sequence (WDMS) binaries provide direct constraints on the outcomes of common-envelope (CE) evolution and the survival of low-mass companions during engulfment. We report the discovery and confirmation of 10 totally eclipsing WD + cool-M-dwarf binaries identified through a search tailored to minute-scale eclipses in Transiting Exoplanet Survey Satellite (TESS) high-cadence data and validated with SPECULOOS multiband photometry. The systems have orbital periods of a few hours and companion masses of 0.094–0.175 M _⊙ . Our pilot search of ∼37,000 Gaia-selected WDs increases the number of WD+M systems first identified through TESS by an order of magnitude, demonstrating that minute-scale WD eclipses occupy a previously underexplored discovery regime for TESS. SPECULOOS follow-up establishes the WDs as the sources of the eclipse signals, while chromatic eclipse dilution and broadband spectral-energy-distribution (SED) modeling provide complementary constraints on the component properties. These systems extend the TESS-discovered eclipsing WD+M population toward lower companion masses and establish an effective, scalable framework for expanding the search from the ∼37,000 WDs analyzed here to a pool of O (10 ⁶ ) Gaia WD candidates with TESS photometry.

White dwarf–brown dwarf (WD+BD) binaries are rare laboratories for probing both substellar survival through post-main-sequence evolution and the physics of strongly irradiated atmospheres. We present time-resolved eclipse photometry and radial-velocity confirmation of J0404+1112, a compact ( P = 2.93 hr), totally eclipsing WD+BD system initially reported in Research Notes of the AAS by J. de Wit et al. New high-cadence observations resolve the total eclipse of the WD and, combined with spectroscopy, broadband photometry, and the Gaia parallax, yield a revised system architecture. We find a hot DA WD with T _eff ≃ 28,000 K, log g ≃ 8.0 , M _WD ≃ 0.6 M _⊙ , and R _WD ≃ 0.015 R _⊙ , orbited by a ∼40 M _Jup BD with radius ∼0.9 R _Jup . These parameters supersede earlier spectral energy distribution (SED)-based estimates in which the WD temperature, radius, distance, and extinction were strongly covariant. We break this degeneracy with normalized Balmer-line profile fitting and high-cadence eclipse photometry that constrains the white dwarf radius geometrically. The total eclipses enable isolation of the brown dwarf (BD) flux and constrain its nightside emission. With its short orbital period and strong irradiation, J0404+1112 provides a uniquely compact, high-sensitivity benchmark for probing atmospheric heat redistribution and photochemistry in the temperature regime of the hottest ultrahot Jupiters, spanning substellar-point and nightside temperatures of ∼3700 K and ∼1750 K within a single ∼3 hr orbit.

We present results from 28 stellar occultations by the large trans-Neptunian object (50000) Quaoar registered between 2018 and 2025. By performing a joint analysis of this occultation dataset, along with nine other published events, we were able to fit an oblate ellipsoid shape, with equatorial semiaxes a and b of 566 . 1 − 2.2 + 2.5 km, and a polar semiaxis, c , of 511 . 2 − 3.7 + 3.6 km. It provides an equivalent volumetric diameter of 1094.4 ± 4.6 km and polar oblateness of 0.097 ± 0.011. Considering an absolute magnitude of H = 2.79 ± 0.35, we derive a geometric albedo of p _V = 0.125 ± 0.038. We have derived new upper limits to the surface pressure of a CH ₄ atmosphere of 0.15 nbar (1 σ ) and 0.65 nbar (3 σ ). We also provide a table with the 36 new astrometric positions for Quaoar. Using the new system mass derived from Weywot’s orbit around Quaoar, we calculated a density of 1.760 ± 0.109 g cm ⁻³ . Moreover, from the derived size and rotation period (8.8394 ± 0.0002 hr, we calculated that, if Quaoar is in Maclaurin hydrostatic equilibrium state, it would have a density of 1.859 ± 0.200 g cm ⁻³ . This result, within the error bars, is compatible with the value we found. Therefore, this work shows that Quaoar can be a Maclaurin object, being eligible as a dwarf planet.

Of the >500 confirmed transiting hot Jupiters and ≈2000 additional candidates today, only 10 are known to have nearby companion planets. The survival of nearby companions means that these hot Jupiters cannot have migrated to their present location via dynamically disruptive high-eccentricity migration but instead have undergone disk migration or formed in situ. The occurrence rate for these nearby companions, therefore, constrains the relative efficiency of different hot Jupiter formation pathways. Here, we perform a uniform box least-squares search for nearby transiting companions to hot Jupiters in the first 5 yr of TESS data. Accounting for observational completeness and detection efficiency, we arrive at an occurrence rate of ( 7.6 − 3.8 + 5.5 ) % , which is a lower limit on the fraction of hot Jupiters that underwent disk migration or in situ formation. Comparing this rate with that derived from transit-timing variation searches suggests that hot Jupiters are likely mostly aligned with their nearby companions, but their apparently higher incidence of grazing transits may point to a slight preferential misalignment. We also synthesize evidence that hot Jupiters with nearby companions may have cold companions at a rate similar to that of other hot Jupiters. Comprehensive transit, radial velocity, and stellar obliquity measurements in hot Jupiter systems with nearby companions will be necessary to fully account for the relative prevalence of proposed hot Jupiter formation pathways.

We characterize the radius-dependent observed transiting eccentricity distribution of 219 warm ( P = 8–50 days) systems with only one transiting planetary candidate identified during Sectors 1–69 of the Transiting Exoplanet Survey Satellite (TESS) mission. Using the “photoeccentric effect” in a hierarchical Bayesian framework, we first model the population using discrete planetary size bins (sub-Neptunes, sub-Saturns, and Jovians). We then develop a continuous mixture model with weights governed by a logistic sigmoid function of radius. We find that the warm-single population is best described by two components: a dominant low-eccentricity mode (〈 e _low 〉 = 0.03 9 − 0.038 + 0.018 ) and a secondary dynamically excited mode (〈 e _high 〉 = 0.46 6 − 0.068 + 0.067 ). The fraction of planets belonging to this high-eccentricity component increases strongly with planet radius, characterized by a transition at a break radius of R _br = 9 . 2 − 1.1 + 1.9 R _⊕ . This trend places warm sub-Saturns predominantly on the same low-eccentricity track as sub-Neptunes. In contrast, warm Jovians (8–16 R _⊕ ) are frequently eccentric, with 6 5 − 12 + 13 % of the population in the high-eccentricity mode. Under the assumption of a two-component model, we see tentative evidence for a bimodal Jovian distribution at ∼2.7 σ . Finally, we identify a nonnegligible tail of highly eccentric sub-Neptunes (1–4 R _⊕ ), which comprise 16 . 2 − 6.4 + 5.2 % of the population, consistent with excitation by nontransiting external companions.