As part of the KESPRINT collaboration, we present the discovery and characterization of three exoplanets in the sub-Neptune to super-Neptune regime, spanning key regions of the exo-Neptunian landscape. TOI-1472c and TOI-1648b are newly discovered sub-Neptunes, while TOI-1472b is a previously known super-Neptune for which we provide an improved mass measurement. These planets have orbital periods of 6–15 days and radii of 2.5–4.1 R_⊕, probing regions where planet formation and atmospheric evolution remain poorly understood. We combine TESS transit photometry with ground-based radial velocities to determine precise masses, radii, and orbital properties. TOI-1472b has a mass of 18.0^+0.84_-0.85 M_⊕ and a radius of 4.06 ± 0.10 R_⊕, TOI-1472c has a mass of 21.1^+0.96_-0.99 M_⊕ and a radius of 3.33 ± 0.08 R_⊕, and TOI-1648b has a mass of 7.4^+1.1_-1.3 M_⊕ and a radius of 2.54^+0.14_-0.12 R_⊕. The planets exhibit a range of eccentricities (0.041–0.178), indicating diverse evolutionary histories. TOI-1648b, with a high Transmission Spectroscopy Metric (TSM ∼59), is a promising target for atmospheric characterization. Together, these three planets provide precise constraints on the structure, composition, and dynamical evolution of small to intermediate-sized exoplanets, enriching our understanding of the exo-Neptunian landscape.

Beyond orbital periods of 10 days, there is a dearth of known transiting gas giants. On longer orbits, planets are less affected by their host star, and become ideal probes of planet formation, migration and evolution. We report the discovery of a long period Neptune and two Saturns, each initially identified as single transits in the TESS photometry, and solved through additional transits from ground-based follow-up photometric observations by NGTS and ASTEP. High-resolution radial velocity mass measurements using CORALIE and HARPS confirm their planetary nature. From joint modelling of the photometric and spectroscopic data, we determine an orbital period of $43.12655_{-0.00017}^{+0.00012}~$days, radius of 3.65 ± 0.22 R⊕, and mass of $19.1_{-4.5}^{+4.9}~\mathrm{M_{\rm{\oplus }}}$ for NGTS-34 b, making it one of the longest period well-characterized transiting Neptunes. Orbiting a late F-type star, bright in the K-band (Kmag ≃ 7.9), it is amenable for cool atmosphere studies using JWST or Ariel. TOI-4940 b is a small Saturn on a $25.867811_{-0.000056}^{+0.000058}~$day orbit with a radius of 6.61 ± 0.37 R⊕ and an upper mass limit <89 M⊕. NGTS-35 b(=TOI-6669 b) is a larger Saturn on a 25.241192 ± 0.000022 day, moderately eccentric orbit ($e = 0.192_{-0.033}^{+0.037}$), with a radius of 10.90 ± 0.65 R⊕ and a mass of $152_{-19}^{+22}~\mathrm{M_{\rm{\oplus }}}$. With an assumed albedo A = 0.3, each of these planets has an equilibrium temperature below 700K, with NGTS-35 b especially cold at 450 K. These three giants add to the small but growing population of long period planets that can further our understanding of planet formation mechanisms.

Context. Characterization of warm giants is crucial to constrain giant planet formation and evolution. Measuring the mass and radius of these planets, combined with their moderated irradiation, allows us to estimate their planetary bulk composition, which is a key quantity to comprehend giant planet formation and structure. Aims. We present the discovery of two transiting warm giant planets orbiting solar-type stars from the Transiting Exoplanet Survey Satellite (TESS), which were characterized by further spectroscopic and photometric ground-based observations. Methods. We performed a joint analysis of photometric data with radial velocities to confirm and characterize TOI-883 b and TOI-899 b, two sub-Saturns orbiting solar-like stars. Results. TOI-883 b and TOI-899 b have masses of 0.123 ± 0.012 M_J and 0.213 ± 0.024 M_J, radius of 0.604 ± 0.028 R_J and 0.991 ± 0.044 R_J, periods of 10.06 d and 12.85 d and equilibrium temperature of 1086 ± 19 K and 1040 ± 19 K, respectively. Conclusions. While having similar masses, orbital periods and stellar host properties, these planets seem to have different internal compositions, which could point to distinct formation histories. Both planets are suitable targets for atmospheric studies to further constrain formation scenarios of planets in the Neptune-Saturn mass range

We present the discovery of TIC-65910228 b / NGTS-38 b, a giant exoplanet with a radius of 1 . 081 +/- 0 . 047 R-J and a mass of 4 . 77(-0.37)(+0 . 39) M-J on a long-period ( 180 . 52797 +/- 0 . 00036 d), moderately eccentric ( e = 0 . 3086 +/- 0 . 010 ) orbit transiting a bright (V=10 . 230 +/- 0 . 020 mag) metal rich ([Fe/H] =0 . 33 +/- 0 . 09 'dex') F6V-F7V type host star. The planet was initially detected from a single transit in TESS Sector 33. A photometric monitoring campaign of 228 nights with NGTS detected a transit egress of the planet, which together with spectroscopic radial velocity monitoring with CORALIE and HARPS identified an orbital period of 180.5 d. These radial velocity measurements also showed the mass of the companion to be planetary. Additional transit observations coordinated by the TESS follow-up observing program allowed further confirmation and refinement of this period. With its relatively cool equilibrium temperature of 457 +/- 11 K, NGTS-38 b joins a small but growing population of well characterized transiting warm-Jupiters and has one of the longest periods of any discovered to date. The target is situated in the LOPS2 field of the upcoming PLATO mission which will allow for greater refinement of the system parameters and potential for the discovery of additional companions too small and/or too long-period to be seen by TESS or NGTS. NGTS-38 b's bright host star and wide orbital separation make it an attractive target for further study, including potential measurement of its spin-orbit alignment or targeted exomoon/ring searches.

We present NGTS measurements of rotation period distributions for FGKM stars in seven young open clusters spanning 40–700 Myr within PLATO's first long-stare LOPS2 field. We measure 1063 rotation periods, of which 479 are newly analysed as part of cluster specific rotation studies, whilst 63 are unique periods not reported in the recent TESS All-Sky Rotation Survey. Of the 1063 rotation periods, 285 are identified as likely binary or higher order multiple systems using colour-magnitude diagrams and Gaia astrometry. These are the first comprehensive rotation period distributions for Trumpler 10, NGC 2451B and Alessi 3, while extending existing distributions for NGC 2451A, NGC 2516, Collinder 135 and IC 2391, to create a fuller picture on the rotation state of young stars in PLATO's LOPS2 field. We find that main-sequence solar-mass stars in the 40 Myr old NGC 2451B cluster, form a slow sequence that can be distinguished from their counterparts at 70–80 Myr, thereby significantly reducing the age at which young stellar groups can be relatively aged via their rotation sequences. We also observe stalled spin down from the age of NGC 2451A to at least that of NGC 2516 ( 70–150 Myr) at masses ≳1 M_⊙, supporting previous predictions that angular momentum redistribution and removal should result in a wave of stalled spin down that propagates as a function of both mass and age. Finally, we provide a new age estimate for Alessi 3 of 687±106 Myr using differential gyrochronology age dating.

Modern scientific CMOS cameras offer very fast readout speeds and low read noise. In this study, we evaluate the performance of the Andor Marana CMOS camera through on-sky testing carried out at the NGTS facility at the ESO Paranal Observatory in Chile. We mount the Marana camera to an NGTS telescope, and conduct photometric observations of bright stars. In particular, we target transit events around eight known bright exoplanet host stars. Simultaneous observations are carried out using an existing Andor iKon-L CCD camera on a neighbouring NGTS telescope. This allows for a direct comparison of the photometric precision between the CMOS and CCD cameras. We find that the Marana CMOS exhibits a similar level of photometric performance to the CCD camera, achieving 500 ppm at a 30-min time-scale for a T $=10$ mag star. Although the CCD has a slightly better quantum efficiency over the NGTS filter range (520-890 nm), we find that the faster readout speed of the CMOS compared to the CCD means that the CMOS camera detects 20 per cent more photons per unit time for a solar-type star in our standard 10 s exposure time operation mode. This results in the CMOS performing slightly better photometry in the photon-limited regime. We conclude that modern CMOS cameras, such as the Marana, are very well-suited for astronomical time-series photometry applications.

The young TOI-451 planetary system, aged 125 Myr, provides a unique opportunity to test theories of planetary internal structures and atmospheric mass-loss through examination of its three transiting planets. We present an exhaustive photometric and spectroscopic follow-up to determine the orbital and physical properties of the system. We perform multidimensional Gaussian Process regression with the code pyaneti on spectroscopic time-series and NGTS/LCO light curves to disentangle the stellar and planetary signal in ESPRESSO radial velocities. We show how contemporaneous photometry serves as an activity indicator to inform RV modelling within a multidimensional Gaussian Processes framework. We argue that this can be exploited when spectroscopic observations are adversely affected by low signal-to-noise and/or poor sampling. We estimate the Doppler semi-amplitudes of $k_{\rm b}=$ $2.6_{-1.2}<^>{+1.1}$ $\mathrm{m\, s<^>{-1}}$, $k_{\rm c}=$ $1.2_{-0.8}<^>{+1.0}$ $\mathrm{m\, s<^>{-1}}$ , and $k_{\rm d}=$ $2.7 \pm 1.2$ $\mathrm{m\, s<^>{-1}}$ . This translates in 2$\sigma$ mass estimates for TOI-451 b and d of $M_{\rm b}=$ $4.7_{-2.2}<^>{+2.1}$ $\mathrm{M_{\rm{\oplus }}}$ and $M_{\rm d}=$ $10.2_{-4.5}<^>{+4.6}$ $\mathrm{M_{\rm{\oplus }}}$; as well as a mass upper limit for TOI-451 c of $M_{\rm c} \lt 11.5\, M_{\rm{\oplus }}$. The derived planetary properties suggest that planets c and d contain significant hydrogen-rich envelopes. The inferred parameters of TOI-451 b are consistent with either a rocky world that still retains a small hydrogen envelope or a water world. These insights make the TOI-451 system an ideal laboratory for future follow-up studies aimed at measuring atmospheric compositions, detecting atmospheric mass-loss signatures, and further exploring planetary formation and evolution processes.

Aims. We reinvestigated the HD 208487 system to test the reality of the proposed HD 208487c world. We also searched for additional companions using applied Bayesian statistics and 15+ years of new radial velocity (RV) data from the HARPS and the PFS instruments that were taken post-discovery of HD 208487b, as part of our continued study of bright Sun-like stars within 50 pc of the Sun. Methods. RV data were analyzed with generalized Lomb-Scargle periodograms, followed by Bayesian analysis techniques using the EMPEROR code. We also scrutinized various stellar activity indices to search for any corresponding peaks in the power spectra, correlations with the RV measurements, or significant signals from a Bayesian analysis methodology. Finally, photometric data were also checked to test for any transits or possible activity manifestations that could lead to possible false RV signals or excess noise. Results. Our analysis points toward a candidate second planet in the system, positioned near the period of a previously proposed and subsequently challenged signal. This signal, HD 208487c, would relate to a cool Saturn world with an orbital period of 923.06-2.76(+2.02) d and a minimum mass of M(j)sini = 0.32 +/- 0.01 M-j. Our analysis also led to a newly discovered candidate planet, HD 208487d, which if confirmed would be the result of a cool super-Neptune-sub-Saturn with a period of 1380.13(-8.25)(+19.20) d and a minimum mass of M(j)sini = 0.15 +/- 0.01 M-j. Neither stellar activity indices nor photometric data show signals statistically matching these periods. We find that stellar activity is indeed affecting the RVs, and yet our joint RV+activity indicator modeling argues they are Doppler in nature. We show that the RV models are stable over long timescales, and these signals are independent of wavelength-dependent noise. The relative contributions of the data to the model were also examined. Conclusions. We uncovered a candidate three-planet system that would consist of an inner gas giant, a central Saturn, and an outer super-Neptune-sub-Saturn. Extensive analysis of both photometric and spectroscopic data as activity proxies strongly supports the planetary system hypothesis; however, more long-term RV data would help add more statistical weight to the reality of candidate planets c and d. Assuming our model best represents reality, a dynamical analysis suggests that gravitational scattering of an initially ordered, equally spaced system in a long resonant chain of six Neptunes can explain the current architecture of HD 208487, a moderately eccentric inner massive planet with an outer nearly resonant (P-d/P-c = 1.495) gas giant and super-Neptune. More RVs may shed light on the reality of a fourth Doppler signal uncovered in the data that sits close to the 2:1 period ratio with signal of HD 208487c.

Context. The proliferation of exoplanet discoveries, particularly within such exotic environments as the Neptune desert, challenges our understanding of planetary atmospheres undergoing intense irradiation. The unexpected discovery of LTT 9779 b, an ultra-hot Neptune deep within this desert offers a prime opportunity for in-depth atmospheric studies. This research builds upon previous observations of LTT9779b from space-based telescopes, including the Transiting Exoplanet Survey Satellite (TESS), Spitzer Space Telescope, and CHaracterising ExOPlanet Satellite (CHEOPS), while incorporating new observations from the Very Large Telescope's (VLT) Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations (ESPRESSO) instrument to delve deeper into the atmospheric dynamics of this intriguing exoplanet. Preliminary analyses suggest a metal-rich atmosphere alongside a notably high day-side geometric albedo that may imply the existence of silicate clouds. Furthermore, there appears to be minimal atmospheric escape, presenting intriguing contrasts to existing models of planetary evolution and atmospheric behaviour under extreme irradiation. Aims. We aim to contribute to the broader understanding of atmospheric compositions and the mechanisms behind the survival of atmospheres in the Neptune desert through detailed spectroscopic analysis. We started by obtaining the transmission spectrum of LTT9779 b between 0.4 and 0.78 micrometres with ESPRESSO on the VLT. Methods. Our analysis addressed systematics in ESPRESSO data across three distinct transit events, focusing on the sodium doublet and hydrogen alpha (H alpha). We also used the cross-correlation method with models that contain Na, K, FeH, TiO, and VO Results. No statistically significant atmospheric signal was detected, with lower limits placed on the atmospheric metallicity established at [Fe/H] >= 2.25, which is >= 180x solar. The non-detection is aligned with a high metallicity atmosphere scenario in a cloud-free model, suggesting a high mean molecular weight and a reduced atmospheric scale height. Conclusions. We interpret the lack of any detection as evidence to support a very high metallicity for the planet's atmosphere. This would give rise to a high mean molecular weight and, hence, a low atmospheric scale height, rendering any signal too weak to be detected. Another possibility is the presence of high-altitude clouds or hazes that would suppress any signal from elements deeper in the atmosphere. These findings are consistent with recent consistent with recent James Webb Space Telescope (JWST) observations, which also report muted spectral features and suggest a high-metallicity atmosphere with clouds at high altitudes. Our results, together with those from JWST, support the hypothesis of a metal-rich atmosphere possibly obscured by clouds or hazes.

We report the discovery and confirmation of two planets orbiting the metal-poor Sun-like star HD 35843 (TOI 4189). HD 35843 c is a temperate sub-Neptune transiting planet with an orbital period of 46.96 days that was first identified by Planet Hunters TESS. We combine data from TESS and follow-up observations to rule out false-positive scenarios and validate the planet. We then use ESPRESSO radial velocities (RVs) to confirm the planetary nature and characterize the planet’s mass and orbit. Further analysis of these RVs reveals the presence of an additional planet, HD 35843 b, with a period of 9.90 days and a minimum mass of 5.84 ± 0.84 M _⊕ . For HD 35843 c, a joint photometric and spectroscopic analysis yields a radius of 2.54 ± 0.08 R _⊕ , a mass of 11.32 ± 1.60 M _⊕ , and an orbital eccentricity of e = 0.15 ± 0.07. With a bulk density of 3.80 ± 0.70 g cm ^−3 , the planet might be rocky with a substantial H _2 atmosphere or it might be a “water world.” With an equilibrium temperature of ∼480 K, HD 35843 c is among the coolest ∼5% of planets discovered by TESS. Combined with the host star’s relative brightness ( V = 9.4), HD 35843 c is a promising target for atmospheric characterization that will probe this sparse population of temperate sub-Neptunes.

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] similar or equal to 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 circle plus. Moreover, radial velocities from ESPRESSO and HARPS reveal a mass of 30.3-2.4+2.2 M circle plus, 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 similar to 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.

Discovering transiting exoplanets with long orbital periods allows us to study warm and cool planetary systems with temperatures similar to the planets in our own Solar system. The TESS mission has photometrically surveyed the entire Southern Ecliptic Hemisphere in Cycle 1 (August 2018 - July 2019), Cycle 3 (July 2020 - June 2021) and Cycle 5 (September 2022 - September 2023). We use the observations from Cycle 1 and Cycle 3 to search for exoplanet systems that show a single transit event in each year - which we call duotransits. The periods of these planet candidates are typically in excess of 20 days, with the lower limit determined by the duration of individual TESS observations. We find 85 duotransit candidates, which span a range of host star brightnesses between 8 < $T_{mag}$ < 14, transit depths between 0.1 per cent and 1.8 per cent, and transit durations between 2 and 10 hours with the upper limit determined by our normalisation function. Of these candidates, 25 are already known, and 60 are new. We present these candidates along with the status of photometric and spectroscopic follow-up.

Long-period transiting exoplanets bridge the gap between the bulk of transit- and Doppler-based exoplanet discoveries, providing key insights into the formation and evolution of planetary systems. The wider separation between these planets and their host stars results in the exoplanets typically experiencing less radiation from their host stars; hence, they should maintain more of their original atmospheres, which can be probed during transit via transmission spectroscopy. Although the known population of long-period transiting exoplanets is relatively sparse, surveys performed by the Transiting Exoplanet Survey Satellite (TESS) and the Next Generation Transit Survey (NGTS) are now discovering new exoplanets to fill in this crucial region of the exoplanetary parameter space. This study presents the detection and characterisation of NGTS-30 b/TOI-4862 b, a new long-period transiting exoplanet detected by following up on a single-transit candidate found in the TESS mission. Through monitoring using a combination of photometric instruments (TESS, NGTS, and EulerCam) and spectroscopic instruments (CORALIE, FEROS, HARPS, and PFS), NGTS-30 b/TOI-4862 b was found to be a long-period (P = 98.29838 day) Jupiter-sized (0.928 RJ; 0.960 MJ) planet transiting a 1.1 Gyr old G-type star. With a moderate eccentricity of 0.294, its equilibrium temperature could be expected to vary from 274 K to 500 K over the course of its orbit. Through interior modelling, NGTS-30 b/TOI-4862 b was found to have a heavy element mass fraction of 0.23 and a heavy element enrichment (Zp/Z_star) of 20, making it metal-enriched compared to its host star. NGTS-30 b/TOI-4862 b is one of the youngest well-characterised long-period exoplanets found to date and will therefore be important in the quest to understanding the formation and evolution of exoplanets across the full range of orbital separations and ages.

ABSTRACT We report the discovery of the most eccentric transiting brown dwarf in the brown dwarf desert, TOI-2490b. The brown dwarf desert is the lack of brown dwarfs around main-sequence stars within $\sim 3$ au and is thought to be caused by differences in formation mechanisms between a star and planet. To date, only $\sim 40$ transiting brown dwarfs have been confirmed. TOI-2490b is a $73.6\pm 2.4$ $M_{\rm J}$, $1.00\pm 0.02$ $R_{\rm J}$ brown dwarf orbiting a $1.004_{-0.022}^{+0.031}$ ${\rm M}_{\odot }$, $1.105_{-0.012}^{+0.012}$ ${\rm R}_{\odot }$ sun-like star on a 60.33 d orbit with an eccentricity of $0.77989\pm 0.00049$. The discovery was detected within Transiting Exoplanet Survey Satellite sectors 5 (30 min cadence) and 32 (2 min and 20 s cadence). It was then confirmed with 31 radial velocity measurements with FEROS by the WINE collaboration and photometric observations with the Next Generation Transit Survey. Stellar modelling of the host star estimates an age of $\sim 8$ Gyr, which is supported by estimations from kinematics likely placing the object within the thin disc. However, this is not consistent with model brown dwarf isochrones for the system age suggesting an inflated radius. Only one other transiting brown dwarf with an eccentricity higher than 0.6 is currently known in the brown dwarf desert. Demographic studies of brown dwarfs have suggested such high eccentricity is indicative of stellar formation mechanisms.

Context . The TOI-178 system consists of a nearby, late-K-dwarf with six transiting planets in the super-Earth to mini-Neptune regime, with radii ranging from to 2.9 R ⊕ and orbital periods between 1.9 and 20.7 days. All the planets, but the innermost one, form a chain of Laplace resonances. The fine-tuning and fragility of such orbital configurations ensure that no significant scattering or collision event has taken place since the formation and migration of the planets in the protoplanetary disc, thereby providing important anchors for planet formation models. Aims . We aim to improve the characterisation of the architecture of this key system and, in particular, the masses and radii of its planets. In addition, since this system is one of the few resonant chains that can be characterised by both photometry and radial velocities, we propose to use it as a test bench for the robustness of the planetary mass determination with each technique. Methods . We performed a global analysis of all the available photometry from CHEOPS, TESS and NGTS, and radial velocity from ESPRESSO, using a photo-dynamical modelling of the light curve. We also tried different sets of priors on the masses and eccentricity, as well as different stellar activity models, to study their effects on the masses estimated by transit-timing variations (TTVs) and radial velocities (RVs). Results . We demonstrate how stellar activity prevents a robust mass estimation for the three outer planets using radial velocity data alone. We also show that our joint photo-dynamical and radial velocity analysis has resulted in a robust mass determination for planets c to 𝑔, with precision of ~ 12% for the mass of planet c, and better than 10% for planets d to 𝑔. The new precisions on the radii range from 2 to 3%. The understanding of this synergy between photometric and radial velocity measurements will be valuable for the PLATO mission. We also show that TOI-178 is indeed currently locked in the resonant configuration, librating around an equilibrium of the chain.

We report the discovery of two new transiting giant exoplanets NGTS-26 b and NGTS-27 b by the Next Generation Transit Survey (NGTS). NGTS-26 b orbits around a G6-type main sequence star every 4.52 days. It has a mass of 0.29(-0.06)(+0.07) M-Jup and a radius of 1.33(-0.05)(+0.06) R-Jup making it a Saturn-mass planet with a highly inflated radius. NGTS-27 b orbits around a slightly evolved G3-type star every 3.37 days. It has a mass of 0.59(-0.07)(+0.10) M-Jup and a radius of 1.40 +/- 0.04 R-Jup, making it a relatively standard hot Jupiter. The transits of these two planetary systems were re-observed and confirmed in photometry by the SAAO 1.0-m telescope, 1.2-m Euler Swiss telescope as well as the TESS spacecraft, and their masses were derived spectroscopically by the CORALIE, FEROS and HARPS spectrographs. Both giant exoplanets are highly irradiated by their host stars and present an anomalously inflated radius, especially NGTS-26 b which is one of the largest objects among peers of similar mass.

In the last few decades, planet search surveys have been focusing on solar-type stars, and only recently the high-mass regimes. This is mostly due to challenges arising from the lack of instrumental precision, and more importantly, the inherent active nature of fast-rotating massive stars. Here, we report NGTS-33b (TOI-6442b), a super-Jupiter planet with mass, radius, and orbital period of 3.6 +/- 0.3 M-J, 1.64 +/- 0.07 R-J, and 2.827972 +/- 0.000001 d, respectively. The host is a fast-rotating (0.6654 +/- 0.0006 d) and hot (T-eff = 7437 +/- 72 K) A9V type star, with a mass and radius of 1.60 +/- 0.11 M-circle dot and 1.47 +/- 0.06 R-circle dot, respectively. Planet structure and gyrochronology models show that NGTS-33 is also very young with age limits of 10-50 Myr. In addition, membership analysis points towards the star being part of the Vela OB2 association, which has an age of similar to 20-35 Myr, thus providing further evidence about the young nature of NGTS-33. Its low bulk density of 0.19 +/- 0.03 g cm(-3) is 13 per cent smaller than expected when compared to transiting hot Jupiters (HJs) with similar masses. Such cannot be solely explained by its age, where an up to 15 per cent inflated atmosphere is expected from planet structure models. Finally, we found that its emission spectroscopy metric is similar to JWST community targets, making the planet an interesting target for atmospheric follow-up. Therefore, NGTS-33b's discovery will not only add to the scarce population of young, massive and HJs, but will also help place further strong constraints on current formation and evolution models for such planetary systems.

We present the discoveries of NGTS-31b(= TOI-2721), and NGTS-32b, two hot Jupiters from the Next Generation Transit Survey (NGTS) transiting slightly evolved stars. The orbital periods, radii, and masses are 4.16 and 3.31 d, 1.61 and 1.42 $R_{J}$, and 1.12 and 0.57 $M_{J}$, respectively. Both planets have an incident stellar flux significantly above the threshold where inflation occurs, with both planets showing signs of inflation. These planets have widely different equilibrium temperatures than other hot Jupiters of similar mass and radius, with NGTS-31b having a significantly lower temperature, and NGTS-32b being hotter. This dichotomy raises the question of how prevalent the roles of other inflation mechanisms are in the radius anomaly phenomena and will help further constrain different inflationary models.

Transiting planets with orbital periods longer than 40 d are extremely rare among the 5000+ planets discovered so far. The lack of discoveries of this population poses a challenge to research into planetary demographics, formation, and evolution. Here, we present the detection and characterization of HD88986\,b, a potentially transiting sub-Neptune, possessing the longest orbital period among known transiting small planets (< 4 oplus $) with a precise mass measurement ($ > 25). Additionally, we identified the presence of a massive companion in a wider orbit around HD88986. To validate this discovery, we used a combination of more than 25 years of extensive radial velocity (RV) measurements (441 SOPHIE data points, 31 ELODIE data points, and 34 HIRES data points), Gaia DR3 data, 21 years of photometric observations with the automatic photoelectric telescope (APT), two sectors of TESS data, and a 7-day observation of CHEOPS. Our analysis reveals that HD88986\,b, based on two potential single transits on sector 21 and sector 48 which are both consistent with the predicted transit time from the RV model, is potentially transiting. The joint analysis of RV and photometric data show that HD88986\,b has a radius of 2.49pm 0.18 oplus $, a mass of 17.2$^ $ M$_ oplus $, and it orbits every 146.05$^ $ d around a subgiant HD88986 which is one of the closest and brightest exoplanet host stars (G2V type, R=1.543 pm 0.065 R$_ odot $, V=$6.47 0.01$ mag, distance=33.37pm 0.04 pc). The nature of the outer, massive companion is still to be confirmed; a joint analysis of RVs, Hipparcos, and Gaia astrometric data shows that with a 3sigma confidence interval, its semi-major axis is between 16.7 and 38.8 au and its mass is between 68 and 284 Jup $. HD88986\,b's wide orbit suggests the planet did not undergo significant mass loss due to extreme-ultraviolet radiation from its host star. Therefore, it probably maintained its primordial composition, allowing us to probe its formation scenario. Furthermore, the cold nature of HD88986\,b (460pm 8\, K), thanks to its long orbital period, will open up exciting opportunities for future studies of cold atmosphere composition characterization. Moreover, the existence of a massive companion alongside HD88986\,b makes this system an interesting case study for understanding planetary formation and evolution.

We present the results from the first two years of the Planet Hunters Next Generation Transit Survey (NGTS) citizen science project, which searches for transiting planet candidates in data from the NGTS by enlisting the help of members of the general public. Over 8000 registered volunteers reviewed 138,198 light curves from the NGTS Public Data Releases 1 and 2. We utilize a user weighting scheme to combine the classifications of multiple users to identify the most promising planet candidates not initially discovered by the NGTS team. We highlight the five most interesting planet candidates detected through this search, which are all candidate short-period giant planets. This includes the TIC-165227846 system that, if confirmed, would be the lowest-mass star to host a close-in giant planet. We assess the detection efficiency of the project by determining the number of confirmed planets from the NASA Exoplanet Archive and TESS Objects of Interest (TOIs) successfully recovered by this search and find that 74% of confirmed planets and 63% of TOIs detected by NGTS are recovered by the Planet Hunters NGTS project. The identification of new planet candidates shows that the citizen science approach can provide a complementary method to the detection of exoplanets with ground-based surveys such as NGTS.