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The stellar obliquity distribution of warm-Jupiter systems is crucial for constraining the dynamical history of Jovian exoplanets, as the warm Jupiters’ tidal detachment likely preserves their primordial obliquity. However, the sample size of warm-Jupiter systems with measured stellar obliquities has historically been limited compared to that of hot Jupiters, particularly in hot-star systems. In this work, we present newly obtained sky-projected stellar obliquity measurements for the warm-Jupiter systems TOI-559, TOI-2025, TOI-2031, TOI-2485, TOI-2524, and TOI-3972, derived from the Rossiter–McLaughlin effect, and show that all six systems display alignment with a median measurement uncertainty of 13°. Combining these new measurements with the set of previously reported stellar obliquity measurements, our analysis reveals that single-star warm-Jupiter systems tend to be aligned, even around hot stellar hosts. This alignment exhibits a 3.4 σ deviation from the T _eff – λ dependency observed in hot-Jupiter systems, where planets around cool stars tend to be aligned, while those orbiting hot stars show considerable misalignment. The current distribution of spin–orbit measurements for Jovian exoplanets indicates that misalignments are neither universal nor primordial phenomena affecting all types of planets. The absence of misalignments in single-star warm-Jupiter systems further implies that many hot Jupiters, by contrast, have experienced a dynamically violent history.

The orbits of close-in exoplanets provide clues to their formation and evolutionary history. Many close-in exoplanets likely formed far out in their protoplanetary disks and migrated to their current orbits, perhaps via high-eccentricity migration (HEM), a process that can also excite obliquities. A handful of known exoplanets are perhaps caught in the act of HEM, as they are observed on highly eccentric orbits with tidal circularization timescales shorter than their ages. One such exoplanet is Kepler-1656 b, which is also the only known nongiant exoplanet ( 0.8 to have its obliquity constrained; expanding this population will help establish the degree to which orbital misalignment accompanies migration. Future work that constrains the mutual inclinations of outer perturbers will be key for distinguishing plausible mechanisms.

We report the discovery and characterization of a small planet, TOI-1408 c, on a 2.2 day orbit located interior to a previously known hot Jupiter, TOI-1408 b ( P = 4.42 days, M = 1.86 ± 0.02 M _Jup , R = 2.4 ± 0.5 R _Jup ) that exhibits grazing transits. The two planets are near 2:1 period commensurability, resulting in significant transit timing variations (TTVs) for both planets and transit duration variations for the inner planet. The TTV amplitude for TOI-1408 c is 15% of the planet’s orbital period, marking the largest TTV amplitude relative to the orbital period measured to date. Photodynamical modeling of ground-based radial velocity (RV) observations and transit light curves obtained with the Transiting Exoplanet Survey Satellite and ground-based facilities leads to an inner planet radius of 2.22 ± 0.06 R _⊕ and mass of 7.6 ± 0.2 M _⊕ that locates the planet into the sub-Neptune regime. The proximity to the 2:1 period commensurability leads to the libration of the resonant argument of the inner planet. The RV measurements support the existence of a third body with an orbital period of several thousand days. This discovery places the system among the rare systems featuring a hot Jupiter accompanied by an inner low-mass planet.

Measuring the obliquities of stars hosting giant planets may shed light on the dynamical history of planetary systems. Significant efforts have been made to measure the obliquities of FGK stars with hot Jupiters, mainly based on observations of the Rossiter–McLaughlin effect. In contrast, M dwarfs with hot Jupiters have hardly been explored because such systems are rare and often not favorable for such precise observations. Here, we report the first detection of the Rossiter–McLaughlin effect for an M dwarf with a hot Jupiter, TOI-4201, using the Gemini-North/MAROON-X spectrograph. We find TOI-4201 to be well aligned with its giant planet, with a sky-projected obliquity of $\lambda =-{3.0}_{-3.2}^{{+3.7}^{\circ}} $ and a true obliquity of $\psi ={21.3}_{-12.8}^{{+12.5}^{\circ}} $ with an upper limit of 40 ^◦ at a 95% confidence level. The result agrees with dynamically quiet formation or tidal obliquity damping that realigned the system. As the first hot Jupiter around an M dwarf with its obliquity measured, TOI-4201b joins the group of aligned giant planets around cool stars ( T _eff < 6250 K), as well as the small but growing sample of planets with relatively high planet-to-star mass ratio ( M _p / M _* ≳ 3 × 10 ^−3 ) that also appear to be mostly aligned.

HD 110067 is the brightest star known to have six transiting planets. Each adjacent pair of planets has a period ratio that is nearly equal to a ratio of small integers, suggesting the planets are in a chain of mean-motion resonances, but the limited time span of the available data has prevented firm conclusions. Here, we show that the requirement of long-term dynamical stability implies that all six planets are very likely to form a resonant chain. Dynamical simulations of nonresonant systems with initial conditions compatible with the available data almost always suffer an instability within 25 Myr (∼0.3% of the system’s age). Assuming the system is in resonance, we place upper limits on the planets’ eccentricities and lower limits on the masses of the planets that have not yet been measured. We also predict the characteristics of transit timing variations and the values of the three-body libration centers.

The distribution of stellar obliquities provides critical insight into the formation and evolution pathways of exoplanets. In the past decade, it was found that hot stars hosting hot Jupiters are more likely to have high obliquities than cool stars, but it is not clear whether this trend exists only for hot Jupiters or holds for other types of planets. In this work, we extend the study of the obliquities of hot (6250–7000 K) stars with transiting super-Earth-sized and sub-Neptune-sized planets. We constrain the obliquity distribution based on measurements of the stars’ projected rotation velocities. Our sample consists of 170 TESS and Kepler planet-hosting stars and 180 control stars chosen to have indistinguishable spectroscopic characteristics. In our analysis, we find evidence suggesting that the planet hosts have a systematically higher $\langle \sin i\rangle $ compared to the control sample. This result implies that the planet hosts tend to have lower obliquities. However, the observed difference in $\langle \sin i\rangle $ is not significant enough to confirm spin–orbit alignment as it is 3.8 σ away from perfect alignment. We also find evidence that within the planet-hosting stars there is a trend of higher obliquity (lower $\langle \sin i\rangle $ ) for the hotter stars ( T _eff > 6250 K) than for the cooler stars in the sample. This suggests that hot stars hosting smaller planets exhibit a broader obliquity distribution ( $\langle \sin i\rangle =0.79\pm 0.053$ ) than cooler planet-hosting stars, indicating that high obliquities are not exclusive to hot Jupiters and instead are more broadly tied to hot stars.

Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period ( P _orb ) of 12.76 days. The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous P _orb from TESS data. We confirmed the transit signal and P _orb using ground-based photometry with MuSCAT2 and MuSCAT3, and validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host star is inactive, with an X-ray-to-bolometric luminosity ratio of $\mathrm{log}{L}_{{\rm{X}}}/{L}_{\mathrm{bol}}\approx -5.7$ . Joint analysis of the light curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R _⊕ , a 3 σ mass upper limit of 3.9 M _⊕ , and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric (TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.

The LHS 1610 system consists of a nearby ( d = 9.7 pc) M5 dwarf hosting a candidate brown dwarf companion in a 10.6 days, eccentric ( e ∼ 0.37) orbit. We confirm this brown dwarf designation and estimate its mass ( ${49.5}_{-3.5}^{+4.3}$ M _Jup ) and inclination (114.5° ${}_{-10.0}^{+7.4}$ ) by combining discovery radial velocities (RVs) from the Tillinghast Reflector Echelle Spectrograph and new RVs from the Habitable-zone Planet Finder with the available Gaia astrometric two-body solution. We highlight a discrepancy between the measurement of the eccentricity from the Gaia two-body solution ( e = 0.52 ± 0.03) and the RV-only solution ( e = 0.3702 ± 0.0003). We discuss possible reasons for this discrepancy, which can be further probed when the Gaia astrometric time series become available as part of Gaia Data Release 4. As a nearby mid-M star hosting a massive short-period companion with a well-characterized orbit, LHS 1610 b is a promising target to look for evidence of sub-Alfvénic interactions and/or auroral emission at optical and radio wavelengths. LHS 1610 has a flare rate (0.28 ± 0.07 flares per day) on the higher end for its rotation period (84 ± 8 days), similar to other mid-M dwarf systems such as Proxima Cen and YZ Ceti that have recent radio detections compatible with star–planet interactions. While available Transiting Exoplanet Survey Satellite photometry is insufficient to determine an orbital phase dependence of the flares, our complete orbital characterization of this system makes it attractive to probe star–companion interactions with additional photometric and radio observations.

The recent discoveries of Neptune-sized ultra-short-period planets (USPs) challenge existing planet formation theories. It is unclear whether these residents of the Hot Neptune Desert have similar origins to smaller, rocky USPs, or if this discrete population is evidence of a different formation pathway altogether. We report the discovery of TOI-3261b, an ultrahot Neptune with an orbital period P = 0.88 day. The host star is a V = 13.2 mag, slightly supersolar metallicity ([Fe/H] ≃0.15), inactive K1.5 main-sequence star at d = 300 pc. Using data from the Transiting Exoplanet Survey Satellite and the Las Cumbres Observatory Global Telescope, we find that TOI-3261b has a radius of ${3.82}_{-0.35}^{+0.42}$ R _⊕ . Moreover, radial velocities from ESPRESSO and HARPS reveal a mass of ${30.3}_{-2.4}^{+2.2}$ M _⊕ , more than twice the median mass of Neptune-sized planets on longer orbits. We investigate multiple mechanisms of mass loss that can reproduce the current-day properties of TOI-3261b, simulating the evolution of the planet via tidal stripping and photoevaporation. Thermal evolution models suggest that TOI-3261b should retain an envelope potentially enriched with volatiles constituting ∼5% of its total mass. This is the second highest envelope mass fraction among ultrahot Neptunes discovered to date, making TOI-3261b an ideal candidate for atmospheric follow-up observations.

TOI-6255 b (GJ 4256) is an Earth-sized planet (1.079 ± 0.065 R _⊕ ) with an orbital period of only 5.7 hr. With the newly commissioned Keck Planet Finder and CARMENES spectrographs, we determine the planet’s mass to be 1.44 ± 0.14 M _⊕ . The planet is just outside the Roche limit, with P _orb / P _Roche = 1.13 ± 0.10. The strong tidal force likely deforms the planet into a triaxial ellipsoid with a long axis that is ∼10% longer than the short axis. Assuming a reduced stellar tidal quality factor ${Q}_{\star }^{{\prime} }\approx {10}^{7}$ , we predict that tidal orbital decay will cause TOI-6255 to reach the Roche limit in roughly 400 Myr. Such tidal disruptions may produce the possible signatures of planet engulfment that have been seen on stars with anomalously high refractory elemental abundances compared to their conatal binary companions. TOI-6255 b is also a favorable target for searching for star–planet magnetic interactions, which might cause interior melting and hasten orbital decay. TOI-6255 b is a top target (with an Emission Spectroscopy Metric of about 24) for phase-curve observations with the James Webb Space Telescope.

The degree of alignment between a star’s spin axis and the orbital plane of its planets (the stellar obliquity) is related to interesting and poorly understood processes that occur during planet formation and evolution. Hot Jupiters orbiting hot stars (≳6250 K) display a wide range of obliquities, while similar planets orbiting cool stars are preferentially aligned. Tidal dissipation is expected to be more rapid in stars with thick convective envelopes, potentially explaining this trend. Evolved stars provide an opportunity to test the damping hypothesis, particularly stars that were hot on the main sequence and have since cooled and developed deep convective envelopes. We present the first systematic study of the obliquities of hot Jupiters orbiting subgiants that recently developed convective envelopes using Rossiter–McLaughlin observations. Our sample includes two newly discovered systems in the Giants Transiting Giants survey (TOI-6029 b, TOI-4379 b). We find that the orbits of hot Jupiters orbiting subgiants that have cooled below ∼6250 K are aligned or nearly aligned with the spin axis of their host stars, indicating rapid tidal realignment after the emergence of a stellar convective envelope. We place an upper limit for the timescale of realignment for hot Jupiters orbiting subgiants at ∼500 Myr. Comparison with a simplified tidal evolution model shows that obliquity damping needs to be ∼4 orders of magnitude more efficient than orbital period decay to damp the obliquity without destroying the planet, which is consistent with recent predictions for tidal dissipation from inertial waves excited by hot Jupiters on misaligned orbits.

M-dwarf stars provide us with an ideal opportunity to study nearby small planets. The HUnting for M Dwarf Rocky planets Using MAROON-X (HUMDRUM) survey uses the MAROON-X spectrograph, which is ideally suited to studying these stars, to measure precise masses of a volume-limited (

Young (

Hot Jupiters were many of the first exoplanets discovered in the 1990s, but in the decades since their discovery the mysteries surrounding their origins have remained. Here we present nine new hot Jupiters (TOI-1855 b, TOI-2107 b, TOI-2368 b, TOI-3321 b, TOI-3894 b, TOI-3919 b, TOI-4153 b, TOI-5232 b, and TOI-5301 b) discovered by NASA’s TESS mission and confirmed using ground-based imaging and spectroscopy. These discoveries are the first in a series of papers named the Migration and Evolution of giant ExoPlanets survey and are part of an ongoing effort to build a complete sample of hot Jupiters orbiting FGK stars, with a limiting Gaia G -band magnitude of 12.5. This effort aims to use homogeneous detection and analysis techniques to generate a set of precisely measured stellar and planetary properties that is ripe for statistical analysis. The nine planets presented in this work occupy a range of masses (0.55 M _J < M _P < 3.88 M _J ) and sizes (0.967 R _J < R _P < 1.438 R _J ) and orbit stars that have an effective temperature in the range of 5360 K < T _eff < 6860 K with Gaia G -band magnitudes ranging from 11.1 to 12.7. Two of the planets in our sample have detectable orbital eccentricity: TOI-3919 b ( $e={0.259}_{-0.036}^{+0.033}$ ) and TOI-5301 b ( $e={0.33}_{-0.10}^{+0.11}$ ). These eccentric planets join a growing sample of eccentric hot Jupiters that are consistent with high-eccentricity tidal migration, one of the three most prominent theories explaining hot Jupiter formation and evolution.

Sub-Neptunes with radii of 2–3 R _⊕ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties and bulk compositions of transiting sub-Neptunes provide clues to the formation and evolution of close-in small planets. In this paper, we present the discovery and follow-up of four sub-Neptunes orbiting M dwarfs (TOI-782, TOI-1448, TOI-2120, and TOI-2406), three of which were newly validated by ground-based follow-up observations and statistical analyses. TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b have radii of ${R}_{{\rm{p}}}={2.740}_{-0.079}^{+0.082}\,{R}_{\oplus }$ , ${2.769}_{-0.068}^{+0.073}\,{R}_{\oplus }$ , 2.120 ± 0.067 R _⊕ , and ${2.830}_{-0.066}^{+0.068}\,{R}_{\oplus }$ and orbital periods of P = 8.02, 8.11, 5.80, and 3.08 days, respectively. Doppler monitoring with the Subaru/InfraRed Doppler instrument led to 2 σ upper limits on the masses of

We report the discovery of the transiting planet GJ 238 b, with a radius of 0.566 ± 0.014 R _⊕ (1.064 ± 0.026 times the radius of Mars) and an orbital period of 1.74 days. The transit signal was detected by the TESS mission and designated TOI-486.01. The star’s position close to the southern ecliptic pole allows for almost continuous observations by TESS when it is observing the southern sky. The host star is an M2.5 dwarf with V = 11.57 ± 0.02 mag, K = 7.030 ± 0.023 mag, a distance of 15.2156 ± 0.0030 pc, a mass of ${0.4193}_{-0.0098}^{+0.0095}$ M _☉ , a radius of ${0.4314}_{-0.0071}^{+0.0075}$ R _☉ , and an effective temperature of 3485 ± 140 K. We validate the planet candidate by ruling out or rendering highly unlikely each of the false positive scenarios, based on archival data and ground-based follow-up observations. Validation was facilitated by the host star’s small size and high proper motion of 892.633 ± 0.025 mas yr ^–1 .

The nearby LHS 1678 (TOI-696) system contains two confirmed planets and a wide-orbit, likely brown-dwarf companion, which orbit an M2 dwarf with a unique evolutionary history. The host star occupies a narrow “gap” in the Hertzsprung–Russell diagram lower main sequence, associated with the M dwarf fully convective boundary and long-term luminosity fluctuations. This system is one of only about a dozen M dwarf multiplanet systems to date that hosts an ultra-short-period planet (USP). Here we validate and characterize a third planet in the LHS 1678 system using TESS Cycle 1 and 3 data and a new ensemble of ground-based light curves. LHS 1678 d is a 0.98 ± 0.07 R _⊕ planet in a 4.97 day orbit, with an insolation flux of ${9.1}_{-0.8}^{+0.9}\,{S}_{\oplus }$ . These properties place it near 4:3 mean motion resonance with LHS 1678 c and in company with LHS 1678 c in the Venus zone. LHS 1678 c and d are also twins in size and predicted mass, making them a powerful duo for comparative exoplanet studies. LHS 1678 d joins its siblings as another compelling candidate for atmospheric measurements with the JWST and mass measurements using high-precision radial velocity techniques. Additionally, USP LHS 1678 b breaks the “peas-in-a-pod” trend in this system although additional planets could fill in the “pod” beyond its orbit. LHS 1678's unique combination of system properties and their relative rarity among the ubiquity of compact multiplanet systems around M dwarfs makes the system a valuable benchmark for testing theories of planet formation and evolution.

We report on the discovery and validation of a transiting long-period mini-Neptune orbiting a bright ( V = 9.0 mag) G dwarf (TOI 4633; R = 1.05 R _⊙ , M = 1.10 M _⊙ ). The planet was identified in data from the Transiting Exoplanet Survey Satellite by citizen scientists taking part in the Planet Hunters TESS project. Modelling of the transit events yields an orbital period of 271.9445 ± 0.0040 days and radius of 3.2 ± 0.20 R _⊕ . The Earth-like orbital period and an incident flux of ${1.56}_{-0.16}^{+0.20}$ F _⊕ places it in the optimistic habitable zone around the star. Doppler spectroscopy of the system allowed us to place an upper mass limit on the transiting planet and revealed a non-transiting planet candidate in the system with a period of 34.15 ± 0.15 days. Furthermore, the combination of archival data dating back to 1905 with new high angular resolution imaging revealed a stellar companion orbiting the primary star with an orbital period of around 230 yr and an eccentricity of about 0.9. The long period of the transiting planet, combined with the high eccentricity and close approach of the companion star makes this a valuable system for testing the formation and stability of planets in binary systems.

Based on photometric observations by TESS, we present the discovery of a potential Venus analog transiting LHS 475, an M3 dwarf located 12.5 pc from the Sun. The mass of the star is 0.274 ± 0.015 M _☉ . The planet, originally reported as TOI 910.01, has an orbital period of 2.0291010 ± 0.0000017 days and an estimated radius of 0.975 ± 0.058 R _⊕ . We confirm the validity and source of the transit signal with MEarth and Las Cumbres Observatory Global Telescope ground-based follow-up photometry. We present radial velocity data from CHIRON that rule out massive companions. In accordance with the observed mass–radius distribution of exoplanets as well as planet formation theory, we expect this planetary companion to be terrestrial, with an estimated radial velocity semiamplitude of 1.1 m s ^−1 . LHS 475 b is likely too hot to be habitable but is a suitable candidate for emission and transmission spectroscopy.

We present and confirm TOI-1751 b, a transiting sub-Neptune orbiting a slightly evolved, solar-type, metal-poor star ( T _eff = 5996 ± 110 K, $\mathrm{log}(g)=4.2\pm 0.1$ , V = 9.3 mag, [Fe/H] = −0.40 ± 0.06 dex) every 37.47 days. We use TESS photometry to measure a planet radius of ${2.77}_{-0.07}^{+0.15}\,{R}_{\oplus }$ . We also use both Keck/HIRES and APF/Levy radial velocities (RV) to derive a planet mass of ${14.5}_{-3.14}^{+3.15}\,{M}_{\oplus }$ , and thus a planet density of 3.6 ± 0.9 g cm ^−3 . There is also a long-period (∼400 days) signal that is observed in only the Keck/HIRES data. We conclude that this long-period signal is not planetary in nature and is likely due to the window function of the Keck/HIRES observations. This highlights the role of complementary observations from multiple observatories to identify and exclude aliases in RV data. Finally, we investigate the potential compositions of this planet, including rocky and water-rich solutions, as well as theoretical irradiated ocean models. TOI-1751 b is a warm sub-Neptune with an equilibrium temperature of ∼820 K. As TOI-1751 is a metal-poor star, TOI-1751 b may have formed in a water-enriched formation environment. We thus favor a volatile-rich interior composition for this planet.

The Transiting Exoplanet Survey Satellite (TESS) continues to increase dramatically the number of known transiting exoplanets, and is optimal for monitoring bright stars amenable to radial velocity (RV) and atmospheric follow-up observations. TOI-1386 is a solar-type (G5V) star that was detected via TESS photometry to exhibit transit signatures in three sectors with a period of 25.84 days. We conducted follow-up RV observations using Keck/High Resolution Echelle Spectrometer (HIRES) as part of the TESS–Keck Survey, collecting 64 RV measurements of TOI-1386 with the HIRES spectrograph over 2.5 yr. Our combined fit of the TOI-1386 photometry and RV data confirm the planetary nature of the detected TESS signal, and provide a mass and radius for planet b of 0.148 ± 0.019 M _J and 0.540 ± 0.017 R _J , respectively, marking TOI-1386 b as a warm sub-Saturn planet. Our RV data further reveal an additional outer companion, TOI-1386 c, with an estimated orbital period of 227.6 days and a minimum mass of 0.309 ± 0.038 M _J . The dynamical modeling of the system shows that the measured system architecture is long-term stable, although there may be substantial eccentricity oscillations of the inner planet due to the dynamical influence of the outer planet.

We present the discovery of TOI-1994b, a low-mass brown dwarf transiting a hot subgiant star on a moderately eccentric orbit. TOI-1994 has an effective temperature of ${7700}_{-410}^{+720}$ K, V magnitude of 10.51 mag and log( g ) of ${3.982}_{-0.065}^{+0.067}$ . The brown dwarf has a mass of ${22.1}_{-2.5}^{+2.6}$ M _J , a period of 4.034 days, an eccentricity of ${0.341}_{-0.059}^{+0.054}$ , and a radius of ${1.220}_{-0.071}^{+0.082}$ R _J . TOI-1994b is more eccentric than other transiting brown dwarfs with similar masses and periods. The population of low-mass brown dwarfs may have properties similar to planetary systems if they were formed in the same way, but the short orbital period and high eccentricity of TOI-1994b may contrast this theory. An evolved host provides a valuable opportunity to understand the influence stellar evolution has on the substellar companion’s fundamental properties. With precise age, mass, and radius, the global analysis and characterization of TOI-1994b augments the small number of transiting brown dwarfs and allows the testing of substellar evolution models.

Young terrestrial worlds are critical test beds to constrain prevailing theories of planetary formation and evolution. We present the discovery of HD 63433 d—a nearby (22 pc), Earth-sized planet transiting a young Sun-like star (TOI-1726, HD 63433). HD 63433 d is the third planet detected in this multiplanet system. The kinematic, rotational, and abundance properties of the host star indicate that it belongs to the young (414 ± 23 Myr) Ursa Major moving group, whose membership we update using new data from the third data release of the Gaia mission and TESS. Our transit analysis of the TESS light curves indicates that HD 63433 d has a radius of 1.1 R _⊕ and closely orbits its host star with a period of 4.2 days. To date, HD 63433 d is the smallest confirmed exoplanet with an age less than 500 Myr, and the nearest young Earth-sized planet. Furthermore, the apparent brightness of the stellar host ( V ≃ 6.9 mag) makes this transiting multiplanet system favorable to further investigations, including spectroscopic follow-up to probe the atmospheric loss in a young Earth-sized world.

We report the discovery of two TESS sub-Neptunes orbiting the early M dwarf TOI-904 (TIC 261257684). Both exoplanets, TOI-904 b and c, were initially observed in TESS Sector 12 with twin sizes of ${2.426}_{-0.157}^{+0.163}$ and ${2.167}_{-0.118}^{+0.130}$ R _⊕ , respectively. Through observations in five additional sectors in the TESS primary mission and the first and second extended missions, the orbital periods of the planets were measured to be 10.887 ± 0.001 and 83.999 ± 0.001 days, respectively. Reconnaissance radial velocity measurements (taken with EULER/CORALIE and SMARTS/CHIRON) and high-resolution speckle imaging with adaptive optics (obtained from SOAR/HRCAM and Gemini South/ZORRO) show no evidence of an eclipsing binary or a nearby companion, which, together with the low false-positive probabilities calculated with the statistical validation software TRICERATOPS, establishes the planetary nature of these candidates. The outer planet, TOI-904 c, is the longest-period M dwarf exoplanet found by TESS, with an estimated equilibrium temperature of 217 K. As the three other validated planets with comparable host stars and orbital periods were observed by Kepler around much dimmer stars ( J _mag > 12), TOI-904 c, orbiting a brighter star ( J _mag = 9.6), is the coldest M dwarf planet easily accessible for atmospheric follow-up. Future mass measurements and transmission spectroscopy of the similar-sized planets in this system could determine whether they are also similar in density and composition, suggesting a common formation pathway, or whether they have distinct origins.

GJ 367 is a bright ( V ≈ 10.2) M1 V star that has been recently found to host a transiting ultra-short period sub-Earth on a 7.7 hr orbit. With the aim of improving the planetary mass and radius and unveiling the inner architecture of the system, we performed an intensive radial velocity follow-up campaign with the HARPS spectrograph—collecting 371 high-precision measurements over a baseline of nearly 3 yr—and combined our Doppler measurements with new TESS observations from sectors 35 and 36. We found that GJ 367 b has a mass of M _b = 0.633 ± 0.050 M _⊕ and a radius of R _b = 0.699 ± 0.024 R _⊕ , corresponding to precisions of 8% and 3.4%, respectively. This implies a planetary bulk density of ρ _b = 10.2 ± 1.3 g cm ^−3 , i.e., 85% higher than Earth’s density. We revealed the presence of two additional non-transiting low-mass companions with orbital periods of ∼11.5 and 34 days and minimum masses of ${M}_{{\rm{c}}}\sin {i}_{{\rm{c}}}$ = 4.13 ± 0.36 M _⊕ and ${M}_{{\rm{d}}}\sin {i}_{{\rm{d}}}$ = 6.03 ± 0.49 M _⊕ , respectively, which lie close to the 3:1 mean motion commensurability. GJ 367 b joins the small class of high-density planets, namely the class of super-Mercuries, being the densest ultra-short period small planet known to date. Thanks to our precise mass and radius estimates, we explored the potential internal composition and structure of GJ 367 b, and found that it is expected to have an iron core with a mass fraction of ${0.91}_{-0.23}^{+0.07}$ . How this iron core is formed and how such a high density is reached is still not clear, and we discuss the possible pathways of formation of such a small ultra-dense planet.

We report the discovery and validation of two long-period giant exoplanets orbiting the early K dwarf TOI-4600 ( V = 12.6, T = 11.9), first detected using observations from the Transiting Exoplanet Survey Satellite (TESS) by the TESS Single Transit Planet Candidate Working Group. The inner planet, TOI-4600 b, has a radius of 6.80 ± 0.31 R _⊕ and an orbital period of 82.69 days. The outer planet, TOI-4600 c, has a radius of 9.42 ± 0.42 R _⊕ and an orbital period of 482.82 days, making it the longest-period confirmed or validated planet discovered by TESS to date. We combine TESS photometry and ground-based spectroscopy, photometry, and high-resolution imaging to validate the two planets. With equilibrium temperatures of 347 K and 191 K, respectively, TOI-4600 b and c add to the small but growing population of temperate giant exoplanets that bridge the gap between hot/warm Jupiters and the solar system’s gas giants. TOI-4600 is a promising target for further transit and precise RV observations to measure the masses and orbits of the planets as well as search for additional nontransiting planets. Additionally, with Transit Spectroscopy Metric values of ∼30, both planets are amenable for atmospheric characterization with JWST. Together, these will lend insight into the formation and evolution of planet systems with multiple giant exoplanets.

Warm Jupiters are close-in giant planets with relatively large planet–star separations (i.e., 10 < a / R _⋆ < 100). Given their weak tidal interactions with their host stars, measurements of stellar obliquity may be used to probe the initial obliquity distribution and dynamical history for close-in gas giants. Using spectroscopic observations, we confirm the planetary nature of TOI-1859b and determine the stellar obliquity of TOI-1859 to be λ = 38.9 ${}_{-2.7}^{+2.8}$ ° relative to its planetary companion using the Rossiter–McLaughlin effect. TOI-1859b is a 64 day warm Jupiter orbiting around a late F dwarf and has an orbital eccentricity of 0.57 ${}_{-0.16}^{+0.12}$ inferred purely from transit light curves. The eccentric and misaligned orbit of TOI-1859b is likely an outcome of dynamical interactions, such as planet–planet scattering and planet–disk resonance crossing.

Misalignments between planetary orbits and the equatorial planes of their host stars are clues about the formation and evolution of planetary systems. Earlier work found evidence for a peak near 90° in the distribution of stellar obliquities, based on frequentist tests. We performed hierarchical Bayesian inference on a sample of 174 planets for which either the full three-dimensional stellar obliquity has been measured (72 planets) or for which only the sky-projected stellar obliquity has been measured (102 planets). We investigated whether the obliquities are best described by a Rayleigh distribution or by a mixture of a Rayleigh distribution representing well-aligned systems and a different distribution representing misaligned systems. The mixture models are strongly favored over the single-component distribution. For the misaligned component, we tried an isotropic distribution and a distribution peaked at 90° and found the evidence to be essentially the same for both models. Thus, our Bayesian inference engine did not find strong evidence favoring a “perpendicular peak,” unlike the frequentist tests. We also investigated selection biases that affect the inferred obliquity distribution, such as the bias of the gravity-darkening method against obliquities near 0° or 180°. Further progress in characterizing the obliquity distribution will probably require the construction of a more homogeneous and complete sample of measurements.

The probability that a Sun-like star has a close-orbiting giant planet (period ≲1 yr) increases with stellar metallicity. Previous work provided evidence that the period distribution of close-orbiting giant planets is also linked to metallicity, hinting that there two formation/evolution pathways for such objects, one of which is more probable in high-metallicity environments. Here, we check for differences in the period distribution of hot Jupiters ( P < 10 days) as a function of host star metallicity, drawing on a sample of 232 transiting hot Jupiters and homogeneously derived metallicities from Gaia Data Release 3. We found no evidence for any metallicity dependence; the period distributions of hot Jupiters around metal-poor and metal-rich stars are indistinguishable. As a byproduct of this study, we provide transformations between metallicities from the Gaia Radial Velocity Spectrograph and from traditional high-resolution optical spectroscopy of main-sequence FGK stars.

TOI-2076 b is a sub-Neptune-sized planet ( R = 2.39 ± 0.10 R _⊕ ) that transits a young (204 ± 50 MYr) bright ( V = 9.2) K-dwarf hosting a system of three transiting planets. Using spectroscopic observations obtained with the NEID spectrograph on the WIYN 3.5 m Telescope, we model the Rossiter–McLaughlin effect of TOI-2076 b, and derive a sky-projected obliquity of $\lambda =-{3}_{-15}^{+16^\circ }$ . Using the size of the star ( R = 0.775 ± 0.015 R _⊙ ), and the stellar rotation period ( P _rot = 7.27 ± 0.23 days), we estimate an obliquity of $\psi ={18}_{-9}^{+10^\circ }$ ( ψ < 34° at 95% confidence), demonstrating that TOI-2076 b is in a well-aligned orbit. Simultaneous diffuser-assisted photometry from the 3.5 m telescope at Apache Point Observatory rules out flares during the transit. TOI-2076 b joins a small but growing sample of young planets in compact multi-planet systems with well-aligned orbits, and is the fourth planet with an age ≲300 Myr in a multi-transiting system with an obliquity measurement. The low obliquity of TOI-2076 b and the presence of transit timing variations in the system suggest the TOI-2076 system likely formed via convergent disk migration in an initially well-aligned disk.

We present the discovery of TOI-3235 b, a short-period Jupiter orbiting an M dwarf with a stellar mass close to the critical mass at which stars transition from partially to fully convective. TOI-3235 b was first identified as a candidate from TESS photometry and confirmed with radial velocities from ESPRESSO and ground-based photometry from HATSouth, MEarth-South, TRAPPIST-South, LCOGT, and ExTrA. We find that the planet has a mass of 0.665 ± 0.025 M _J and a radius of 1.017 ± 0.044 R _J . It orbits close to its host star, with an orbital period of 2.5926 days but has an equilibrium temperature of ≈ 604 K, well below the expected threshold for radius inflation of hot Jupiters. The host star has a mass of 0.3939 ± 0.0030 M _☉ , a radius of 0.3697 ± 0.0018 R _☉ , an effective temperature of 3389 K, and a J -band magnitude of 11.706 ± 0.025. Current planet formation models do not predict the existence of gas giants such as TOI-3235 b around such low-mass stars. With a high transmission spectroscopy metric, TOI-3235 b is one of the best-suited giants orbiting M dwarfs for atmospheric characterization.

We report the discovery of TOI-700 e, a 0.95 R _⊕ planet residing in the Optimistic Habitable Zone (HZ) of its host star. This discovery was enabled by multiple years of monitoring from NASA’s Transiting Exoplanet Survey Satellite (TESS) mission. The host star, TOI-700 (TIC 150428135), is a nearby (31.1 pc), inactive, M2.5 dwarf ( V _mag = 13.15). TOI-700 is already known to host three planets, including the small, HZ planet, TOI-700 d. The new planet has an orbital period of 27.8 days, and based on its radius (0.95 R _⊕ ), it is likely rocky. TOI-700 was observed for 21 sectors over Years 1 and 3 of the TESS mission, including 10 sectors at 20 s cadence in Year 3. Using this full set of TESS data and additional follow-up observations, we identify, validate, and characterize TOI-700 e. This discovery adds another world to the short list of small, HZ planets transiting nearby and bright host stars. Such systems, where the stars are bright enough that follow-up observations are possible to constrain planet masses and atmospheres using current and future facilities, are incredibly valuable. The presence of multiple small, HZ planets makes this system even more enticing for follow-up observations.

We report the discovery of a super-Jovian 2:1 mean-motion resonance (MMR) pair around the G-type star TIC 279401253, whose dynamical architecture is a prospective benchmark for planet formation and orbital evolution analysis. The system was discovered thanks to a single-transit event recorded by the Transiting Exoplanet Survey Satellite mission, which pointed to a Jupiter-sized companion with poorly constrained orbital parameters. We began ground-based precise radial velocity (RV) monitoring with HARPS and FEROS within the Warm gIaNts with tEss survey to constrain the transiting body’s period, mass, and eccentricity. The RV measurements revealed not one but two massive planets with periods of ${76.80}_{-0.06}^{+0.06}$ and ${155.3}_{-0.7}^{+0.7}$ days, respectively. A combined analysis of transit and RV data yields an inner transiting planet with a mass of ${6.14}_{-0.42}^{+0.39}$ M _Jup and a radius of ${1.00}_{-0.04}^{+0.04}$ R _Jup , and an outer planet with a minimum mass of ${8.02}_{-0.18}^{+0.18}$ M _Jup , indicating a massive giant pair. A detailed dynamical analysis of the system reveals that the planets are locked in a strong first-order, eccentricity-type 2:1 MMR, which makes TIC 279401253 one of the rare examples of truly resonant architectures supporting disk-induced planet migration. The bright host star, V ≈ 11.9 mag, the relatively short orbital period ( P _b = ${76.80}_{-0.06}^{+0.06}$ days), and pronounced eccentricity ( e = 0.448 ${}_{-0.029}^{+0.028}$ ) make the transiting planet a valuable target for atmospheric investigation with the James Webb Space Telescope and ground-based extremely large telescopes.

Complex periodic variables (CPVs) are stars that exhibit highly structured and periodic optical light curves. Previous studies have indicated that these stars are typically disk-free pre-main-sequence M dwarfs with rotation periods ranging from 0.2 to 2 days. To advance our understanding of these enigmatic objects, we conducted a blind search using TESS 2 minute data of 65,760 K and M dwarfs with T

Stellar activity interferes with precise radial velocity measurements and limits our ability to detect and characterize planets, in particular Earth-like planets. We introduce AESTRA (Auto-Encoding STellar Radial-velocity and Activity), a deep-learning method for precise radial velocity measurements. It combines a spectrum autoencoder, which learns to create realistic models of the star’s rest-frame spectrum, and a radial-velocity estimator, which learns to identify true Doppler shifts in the presence of spurious shifts due to line-profile variations. Being self-supervised, AESTRA does not need “ground truth” radial velocities for training, making it applicable to exoplanet host stars for which the truth is unknown. In tests involving 1000 simulated spectra, AESTRA can detect planetary signals as low as 0.1 m s ^−1 even in the presence of 3 m s ^−1 of activity-induced noise and 0.3 m s ^−1 of photon noise per spectrum.

We report the discovery and characterization of three giant exoplanets orbiting solar-analog stars, detected by the TESS space mission and confirmed through ground-based photometry and radial velocity measurements taken at La Silla observatory with FEROS. TOI-2373 b is a warm Jupiter orbiting its host star every ∼13.3 days, and is one of the most massive known exoplanet with a precisely determined mass and radius around a star similar to the Sun, with an estimated mass of m _p = ${9.3}_{-0.2}^{+0.2}\,{M}_{\mathrm{jup}}$ and a radius of r _p = ${0.93}_{-0.2}^{+0.2}\,{R}_{\mathrm{jup}}$ . With a mean density of $\rho ={14.4}_{-1.0}^{+0.9}\,{\rm{g}}\,{\mathrm{cm}}^{-3}$ , TOI-2373 b is among the densest planets discovered so far. TOI-2416 b orbits its host star on a moderately eccentric orbit with a period of ∼8.3 days and an eccentricity of e = ${0.32}_{-0.02}^{+0.02}$ . TOI-2416 b is more massive than Jupiter with m _p = ${3.0}_{-0.09}^{+0.10}\,{M}_{\mathrm{jup}}$ , however is significantly smaller with a radius of r _p = ${0.88}_{-0.02}^{+0.02},{R}_{\mathrm{jup}}$ , leading to a high mean density of $\rho ={5.4}_{-0.3}^{+0.3}\,{\rm{g}}\,{\mathrm{cm}}^{-3}$ . TOI-2524 b is a warm Jupiter near the hot Jupiter transition region, orbiting its star every ∼7.2 days on a circular orbit. It is less massive than Jupiter with a mass of m _p = ${0.64}_{-0.04}^{+0.04}\,{M}_{\mathrm{jup}}$ , and is consistent with an inflated radius of r _p = ${1.00}_{-0.03}^{+0.02}\,{R}_{\mathrm{jup}}$ , leading to a low mean density of $\rho ={0.79}_{-0.08}^{+0.08}\,{\rm{g}}\,{\mathrm{cm}}^{-3}$ . The newly discovered exoplanets TOI-2373 b, TOI-2416 b, and TOI-2524 b have estimated equilibrium temperatures of ${860}_{-10}^{+10}$ K, ${1080}_{-10}^{+10}$ K, and ${1100}_{-20}^{+20}$ K, respectively, placing them in the sparsely populated transition zone between hot and warm Jupiters.

Large-scale exoplanet surveys like the Transiting Exoplanet Survey Satellite (TESS) mission are powerful tools for discovering large numbers of exoplanet candidates. Single-transit events are commonplace within the resulting candidate list due to the unavoidable limitation of the observing baseline. These single-transit planets often remain unverified due to their unknown orbital periods and consequent difficulty in scheduling follow-up observations. In some cases, radial velocity (RV) follow up can constrain the period enough to enable a future targeted transit detection. We present the confirmation of one such planet: TOI-2010 b. Nearly three years of RV coverage determined the period to a level where a broad window search could be undertaken with the Near-Earth Object Surveillance Satellite, detecting an additional transit. An additional detection in a much later TESS sector solidified our final parameter estimation. We find TOI-2010 b to be a Jovian planet ( M _P = 1.29 M _Jup , R _P = 1.05 R _Jup ) on a mildly eccentric orbit ( e = 0.21) with a period of P = 141.83403 days. Assuming a simple model with no albedo and perfect heat redistribution, the equilibrium temperature ranges from about 360 to 450 K from apastron to periastron. Its wide orbit and bright host star ( V = 9.85) make TOI-2010 b a valuable test bed for future low-insolation atmospheric analysis.

While secondary mass inferences based on single-lined spectroscopic binary (SB1) solutions are subject to $\sin i$ degeneracies, this degeneracy can be lifted through the observations of eclipses. We combine the subset of Gaia Data Release 3 SB1 solutions consistent with brown dwarf-mass secondaries with the Transiting Exoplanet Survey Satellite (TESS) Object of Interest (TOI) list to identify three candidate transiting brown dwarf systems. Ground-based precision radial velocity follow-up observations confirm that TOI-2533.01 is a transiting brown dwarf with $M={72}_{-3}^{+3}\,{M}_{\mathrm{Jup}}={0.069}_{-0.003}^{+0.003}\,{M}_{\odot }$ orbiting TYC 2010-124-1 and that TOI-5427.01 is a transiting very low-mass star with $M={93}_{-2}^{+2}\,{M}_{\mathrm{Jup}}={0.088}_{-0.002}^{+0.002}\,{M}_{\odot }$ orbiting UCAC4 515-012898. We validate TOI-1712.01 as a very low-mass star with $M={82}_{-7}^{+7}\,{M}_{\mathrm{Jup}}={0.079}_{-0.007}^{+0.007}\,{M}_{\odot }$ transiting the primary in the hierarchical triple system BD+45 1593. Even after accounting for third light, TOI-1712.01 has a radius nearly a factor of 2 larger than predicted for isolated stars with similar properties. We propose that the intense instellation experienced by TOI-1712.01 diminishes the temperature gradient near its surface, suppresses convection, and leads to its inflated radius. Our analyses verify Gaia DR3 SB1 solutions in the low Doppler semiamplitude limit, thereby providing the foundation for future joint analyses of Gaia radial velocities and Kepler, K2, TESS, and PLAnetary Transits and Oscillations light curves for the characterization of transiting massive brown dwarfs and very low-mass stars.

We present the spectroscopic confirmation and precise mass measurement of the warm giant planet TOI-199 b. This planet was first identified in TESS photometry and confirmed using ground-based photometry from ASTEP in Antarctica including a full 6.5 hr long transit, PEST, Hazelwood, and LCO; space photometry from NEOSSat; and radial velocities (RVs) from FEROS, HARPS, CORALIE, and CHIRON. Orbiting a late G-type star, TOI-199 b has a ${104.854}_{-0.002}^{+0.001}\,{\rm{day}}$ period, a mass of 0.17 ± 0.02 M _J , and a radius of 0.810 ± 0.005 R _J . It is the first warm exo-Saturn with a precisely determined mass and radius. The TESS and ASTEP transits show strong transit timing variations (TTVs), pointing to the existence of a second planet in the system. The joint analysis of the RVs and TTVs provides a unique solution for the nontransiting companion TOI-199 c, which has a period of ${273.69}_{-0.22}^{+0.26}\,{\rm{days}}$ and an estimated mass of ${0.28}_{-0.01}^{+0.02}\,{M}_{{\rm{J}}}$ . This period places it within the conservative habitable zone.

We report the detection and validation of two planets orbiting TOI-2095 (TIC 235678745). The host star is a 3700 K M1V dwarf with a high proper motion. The star lies at a distance of 42 pc in a sparsely populated portion of the sky and is bright in the infrared ( K = 9). With data from 24 sectors of observation during Cycles 2 and 4 of the Transiting Exoplanet Survey Satellite, TOI-2095 exhibits two sets of transits associated with super-Earth-sized planets. The planets have orbital periods of 17.7 days and 28.2 days and radii of 1.30 R _⊕ and 1.39 R _⊕ , respectively. Archival data, preliminary follow-up observations, and vetting analyses support the planetary interpretation of the detected transit signals. The pair of planets have estimated equilibrium temperatures of approximately 400 K, with stellar insolations of 3.23 and 1.73 S _⊕ , placing them in the Venus zone. The planets also lie in a radius regime signaling the transition between rock-dominated and volatile-rich compositions. They are thus prime targets for follow-up mass measurements to better understand the properties of warm, transition-radius planets. The relatively long orbital periods of these two planets provide crucial data that can help shed light on the processes that shape the composition of small planets orbiting M dwarfs.

We present the discovery of TOI-1420b, an exceptionally low-density ( ρ = 0.08 ± 0.02 g cm ^−3 ) transiting planet in a P = 6.96 days orbit around a late G-dwarf star. Using transit observations from TESS, LCOGT, Observatoire Privé du Mont, Whitin, Wendelstein, OAUV, Ca l’Ou, and KeplerCam, along with radial velocity observations from HARPS-N and NEID, we find that the planet has a radius of R _p = 11.9 ± 0.3 R _⊕ and a mass of M _p = 25.1 ± 3.8 M _⊕ . TOI-1420b is the largest known planet with a mass less than 50 M _⊕ , indicating that it contains a sizeable envelope of hydrogen and helium. We determine TOI-1420b’s envelope mass fraction to be ${f}_{\mathrm{env}}={82}_{-6}^{+7} \% $ , suggesting that runaway gas accretion occurred when its core was at most four to five times the mass of the Earth. TOI-1420b is similar to the planet WASP-107b in mass, radius, density, and orbital period, so a comparison of these two systems may help reveal the origins of close-in low-density planets. With an atmospheric scale height of 1950 km, a transmission spectroscopy metric of 580, and a predicted Rossiter–McLaughlin amplitude of about 17 m s ^−1 , TOI-1420b is an excellent target for future atmospheric and dynamical characterization.

We present the discovery from the TESS mission of two giant planets transiting M-dwarf stars: TOI 4201 b and TOI 5344 b. We also provide precise radial velocity measurements and updated system parameters for three other M dwarfs with transiting giant planets: TOI 519, TOI 3629, and TOI 3714. We measure planetary masses of 0.525 ± 0.064 M _J , 0.243 ± 0.020 M _J , 0.689 ± 0.030 M _J , 2.57 ± 0.15 M _J , and 0.412±0.040 M _J for TOI 519 b, TOI 3629 b, TOI 3714 b, TOI 4201 b, and TOI 5344 b, respectively. The corresponding stellar masses are 0.372 ± 0.018 M _☉ , 0.635 ± 0.032 M _☉ , 0.522 ± 0.028 M _☉ , 0.626 ± 0.033 M _☉ , and 0.612 ± 0.034 M _☉ . All five hosts have supersolar metallicities, providing further support for recent findings that, like for solar-type stars, close-in giant planets are preferentially found around metal-rich M-dwarf host stars. Finally, we describe a procedure for accounting for systematic errors in stellar evolution models when those models are included directly in fitting a transiting planet system.

Observations and statistical studies have shown that giant planets are rare around M dwarfs compared with Sun-like stars. The formation mechanism of these extreme systems has remained under debate for decades. With the help of the TESS mission and ground-based follow-up observations, we report the discovery of TOI-4201b, the most massive and densest hot Jupiter around an M dwarf known so far with a radius of 1.22 ± 0.04 R _J and a mass of 2.48 ± 0.09 M _J , about 5 times heavier than most other giant planets around M dwarfs. It also has the highest planet-to-star mass ratio ( q ∼ 4 × 10 ^−3 ) among such systems. The host star is an early M dwarf with a mass of 0.61 ± 0.02 M _⊙ and a radius of 0.63 ± 0.02 R _⊙ . It has significant supersolar iron abundance ([Fe/H] = 0.52 ± 0.08 dex). However, interior structure modeling suggests that its planet TOI-4201b is metal-poor, which challenges the classical core-accretion correlation of stellar−planet metallicity, unless the planet is inflated by additional energy sources. Building on the detection of this planet, we compare the stellar metallicity distribution of four planetary groups: hot/warm Jupiters around G/M dwarfs. We find that hot/warm Jupiters show a similar metallicity dependence around G-type stars. For M-dwarf host stars, the occurrence of hot Jupiters shows a much stronger correlation with iron abundance, while warm Jupiters display a weaker preference, indicating possible different formation histories.

One possible formation mechanism for Hot Jupiters is that high-eccentricity gas giants experience tidal interactions with their host star that cause them to lose orbital energy and migrate inwards. We study these types of tidal interactions in an eccentric Hot Jupiter called HAT-P-2 b, which is a system where a long-period companion has been suggested and hints of orbital evolution were detected. Using 5 additional years of radial velocity (RV) measurements, we further investigate these phenomena. We investigated the long-period companion by jointly fitting RVs and Hipparcos-Gaia astrometry and confirmed this long-period companion, significantly narrowed down the range of possible periods ( ${P}_{2}={8500}_{-1500}^{+2600}$ days), and determined that it must be a substellar object ( ${10.7}_{-2.2}^{+5.2}$ M _j ). We also developed a modular pipeline to simultaneously model rapid orbital evolution and the long-period companion. We find that the rate and significance of evolution are highly dependent on the long-period companion modeling choices. In some cases the orbital rates of change reached ${de}/{dt}\,=\,{3.28}_{-1.72}^{+1.75}\times {10}^{-3}$ yr ^−1 , d ω / dt = 1.12° ± 0.22° yr ^−1 , which corresponds to a ∼321 yr apsidal precession period. In other cases, the data is consistent with de / dt = 7.67 ± 18.6 × 10 ^−4 yr ^−1 , d ω / dt = 0.76° ± 0.24° yr ^−1 . The most rapid changes found are significantly larger than the expected relativistic precession rate and could be caused by transient tidal planet–star interactions. To definitively determine the magnitude and significance of potential orbital evolution in HAT-P-2 b, we recommend further monitoring with RVs and precise transit and eclipse timings.

During its 2 yr Prime Mission, TESS observed over 232,000 stars at a 2 minute cadence across ∼70% of the sky. These data provide a record of photometric variability across a range of astrophysically interesting timescales, probing stellar rotation, stellar binarity, and pulsations. We have analyzed the TESS 2 minute light curves to identify periodic variability on timescales of 0.01–13 days, and explored the results across various stellar properties. We have identified over 46,000 periodic variables with high confidence, and another 38,000 with moderate confidence. These light curves show differences in variability type across the Hertzsprung–Russell diagram, with distinct groupings of rotational, eclipsing, and pulsational variables. We also see interesting patterns across period–luminosity space, with clear correlations between period and luminosity for high-mass pulsators, evolved stars, and contact binary systems, a discontinuity corresponding to the Kraft break, and a lower occurrence of periodic variability in main-sequence stars on timescales of 1.5–2 days. The variable stars identified in this work are cross-identified with several other variability catalogs, from which we find good agreement between the measured periods of variability. There are ∼65,000 variable stars that are newly identified in this work, which includes the rotation rates of low-mass stars, high-frequency pulsation periods for high-mass stars, and a variety of giant star variability.

We report the discovery and Doppler mass measurement of a 7.4 days 2.3 R _⊕ mini-Neptune around a metal-poor K dwarf BD+29 2654 (TOI-2018). Based on a high-resolution Keck/HIRES spectrum, the Gaia parallax, and multiwavelength photometry from the UV to the mid-infrared, we found that the host star has ${T}_{\mathrm{eff}}={4174}_{-42}^{+34}$ K, $\mathrm{log}g={4.62}_{-0.03}^{+0.02}$ , [Fe/H] = − 0.58 ± 0.18, M _* = 0.57 ± 0.02 M _⊙ , and R _* = 0.62 ± 0.01 R _⊙ . Precise Doppler measurements with Keck/HIRES revealed a planetary mass of M _p = 9.2 ± 2.1 M _⊕ for TOI-2018 b. TOI-2018 b has a mass and radius that are consistent with an Earthlike core, with a ∼1%-by-mass hydrogen/helium envelope or an ice–rock mixture. The mass of TOI-2018 b is close to the threshold for runaway accretion and hence giant planet formation. Such a threshold is predicted to be around 10 M _⊕ or lower for a low-metallicity (low-opacity) environment. If TOI-2018 b is a planetary core that failed to undergo runaway accretion, it may underline the reason why giant planets are rare around low-metallicity host stars (one possibility is their shorter disk lifetimes). With a K -band magnitude of 7.1, TOI-2018 b may be a suitable target for transmission spectroscopy with the James Webb Space Telescope. The system is also amenable to metastable Helium observation; the detection of a Helium exosphere would help distinguish between a H/He-enveloped planet and a water world.

We report the confirmation of a TESS-discovered transiting super-Earth planet orbiting a mid-G star, HD 307842 (TOI-784). The planet has a period of 2.8 days, and the radial velocity (RV) measurements constrain the mass to be ${9.67}_{-0.82}^{+0.83}\ {M}_{\oplus }$ . We also report the discovery of an additional planet candidate on an outer orbit that is most likely nontransiting. The possible periods of the planet candidate are approximately 20–63 days, with the corresponding RV semiamplitudes expected to range from 3.2 to 5.4 m s ^−1 and minimum masses from 12.6 to 31.1 M _⊕ . The radius of the transiting planet (planet b) is ${1.93}_{-0.09}^{+0.11}\ {R}_{\oplus }$ , which results in a mean density of ${7.4}_{-1.2}^{+1.4}\ {\rm{g}}\,{\mathrm{cm}}^{-3}$ suggesting that TOI-784 b is likely to be a rocky planet though it has a comparable radius to a sub-Neptune. We found TOI-784 b is located at the lower edge of the so-called “radius valley” in the radius versus insolation plane, which is consistent with the photoevaporation or core-powered mass-loss prediction. The TESS data did not reveal any significant transit signal of the planet candidate, and our analysis shows that the orbital inclinations of planet b and the planet candidate are ${88.60^\circ }_{-0.86}^{+0.84}$ and ≤88.°3–89.°2, respectively. More RV observations are needed to determine the period and mass of the second object, and search for additional planets in this system.

We present the discovery and characterization of HIP 33609 b, a transiting warm brown dwarf orbiting a late B star, discovered by NASA's Transiting Exoplanet Survey Satellite as TOI-588 b. HIP 33609 b is a large ( R _b = ${1.580}_{-0.070}^{+0.074}$ R _J ) brown dwarf on a highly eccentric ( e = ${0.560}_{-0.031}^{+0.029}$ ) orbit with a 39 days period. The host star is a bright ( V = 7.3 mag), T _eff = 10,400 ${}_{-660}^{+800}$ K star with a mass of M _* = ${2.383}_{-0.095}^{+0.10}$ M _⊙ and radius of R _* = ${1.863}_{-0.082}^{+0.087}$ R _⊙ , making it the hottest transiting brown dwarf host star discovered to date. We obtained radial velocity measurements from the CHIRON spectrograph confirming the companion's mass of M _b = ${68.0}_{-7.1}^{+7.4}$ M _J as well as the host star's rotation rate ( $v\sin {i}_{* }=55.6\pm 1.8$ km s ^−1 ). We also present the discovery of a new comoving group of stars, designated as MELANGE-6, and determine that HIP 33609 is a member. We use a combination of rotation periods and isochrone models fit to the cluster members to estimate an age of 150 ± 25 Myr. With a measured mass, radius, and age, HIP 33609 b becomes a benchmark for substellar evolutionary models.

We report the discovery of TOI-4127 b, which is a transiting, Jupiter-sized exoplanet on a long-period ( $P={56.39879}_{-0.00010}^{+0.00010}$ days) and a high-eccentricity orbit around a late F-type dwarf star. This warm Jupiter was first detected and identified as a promising candidate from a search for single-transit signals in TESS Sector 20 data, and was later characterized as a planet following two subsequent transits (TESS Sectors 26 and 53) and follow-up ground-based RV observations with the NEID and SOPHIE spectrographs. We jointly fit the transit and RV data to constrain the physical ( ${R}_{p}={1.096}_{-0.032}^{+0.039}{R}_{{\rm{J}}}$ , ${M}_{p}={2.30}_{-0.11}^{+0.11}{M}_{{\rm{J}}}$ ) and orbital parameters of the exoplanet. Given its high orbital eccentricity ( $e={0.7471}_{-0.0086}^{+0.0078}$ ), TOI-4127 b is a compelling candidate for studies of warm Jupiter populations and of hot Jupiter formation pathways. We show that the present periastron separation of TOI-4127 b is too large for high-eccentricity tidal migration to circularize its orbit, and that TOI-4127 b is unlikely to be a hot Jupiter progenitor unless it is undergoing angular momentum exchange with an undetected outer companion. Although we find no evidence for an external companion, the available observational data are insufficient to rule out the presence of a perturber that can excite eccentricity oscillations and facilitate tidal migration.

We report the discovery and orbital characterization of three new transiting warm giant planets. These systems were initially identified as presenting single-transit events in the light curves generated from the full-frame images of the Transiting Exoplanet Survey Satellite. Follow-up radial velocity measurements and additional light curves were used to determine the orbital periods and confirm the planetary nature of the candidates. The planets orbit slightly metal-rich late F- and early G-type stars. We find that TOI 4406b has a mass of M _P = 0.30 ± 0.04 M _J , a radius of R _P = 1.00 ± 0.02 R _J , and a low-eccentricity orbit ( e = 0.15 ± 0.05) with a period of P = 30.08364 ±0.00005 days. TOI 2338b has a mass of M _P = 5.98 ± 0.20 M _J , a radius of R _P = 1.00 ± 0.01 R _J , and a highly eccentric orbit ( e = 0.676 ± 0.002) with a period of P = 22.65398 ± 0.00002 days. Finally, TOI 2589b has a mass of M _P = 3.50 ± 0.10 M _J , a radius of R _P = 1.08 ± 0.03 R _J , and an eccentric orbit ( e = 0.522 ± 0.006) with a period of P = 61.6277 ± 0.0002 days. TOI 4406b and TOI 2338b are enriched in metals compared to their host stars, while the structure of TOI 2589b is consistent with having similar metal enrichment to its host star.