Explore the vast range of titles available.

Three Earth-sized planets—receiving similar irradiation to Venus and Earth, and ideally suited for atmospheric study—have been found transiting a nearby ultracool dwarf star that has a mass of only eight per cent of that of the Sun. Three planets to watch Theory predicts that terrestrial or rocky planets are likely to be orbiting the lowest-mass stars. This paper reports the detection of a system of three Earth-sized planets transiting a very nearby (12 parsec) ultracool dwarf star of only 8% of the mass of the Sun. The planets are similar in irradiation to Venus and Earth, and particularly well suited for detailed atmospheric characterization. Star-like objects with effective temperatures of less than 2,700 kelvin are referred to as ‘ultracool dwarfs’ 1 . This heterogeneous group includes stars of extremely low mass as well as brown dwarfs (substellar objects not massive enough to sustain hydrogen fusion), and represents about 15 per cent of the population of astronomical objects near the Sun 2 . Core-accretion theory predicts that, given the small masses of these ultracool dwarfs, and the small sizes of their protoplanetary disks 3 , 4 , there should be a large but hitherto undetected population of terrestrial planets orbiting them 5 —ranging from metal-rich Mercury-sized planets 6 to more hospitable volatile-rich Earth-sized planets 7 . Here we report observations of three short-period Earth-sized planets transiting an ultracool dwarf star only 12 parsecs away. The inner two planets receive four times and two times the irradiation of Earth, respectively, placing them close to the inner edge of the habitable zone of the star 8 . Our data suggest that 11 orbits remain possible for the third planet, the most likely resulting in irradiation significantly less than that received by Earth. The infrared brightness of the host star, combined with its Jupiter-like size, offers the possibility of thoroughly characterizing the components of this nearby planetary system.

A longitudinal thermal brightness map of the super-Earth exoplanet 55 Cancri e reveals strong day–night temperature contrast, indicating inefficient heat redistribution consistent with 55 Cancri e either being devoid of atmosphere or having an optically thick atmosphere with heat recirculation confined to the planetary dayside. Night and day on a super-Earth Super-Earth 55 Cancri e is a nearby exoplanet with a diameter less than around twice that of Earth, but a mass that is about eight times Earth's mass. 55 Cancri e is among the best candidates for the study of the nature of a class of exoplanets that is unknown to our Solar System: previous observations of super-Earths have yielded only featureless spectra. Here Brice-Olivier Demory et al . report a longitudinal thermal brightness map of 55 Cancri e in transit across its host star. The map reveals strong day–night temperature contrast, suggesting inefficient heat redistribution consistent with the planet either lacking an atmosphere, or having an optically thick atmosphere with heat recirculation confined to the planetary dayside. Over the past decade, observations of giant exoplanets (Jupiter-size) have provided key insights into their atmospheres 1 , 2 , but the properties of lower-mass exoplanets (sub-Neptune) remain largely unconstrained because of the challenges of observing small planets. Numerous efforts to observe the spectra of super-Earths—exoplanets with masses of one to ten times that of Earth—have so far revealed only featureless spectra 3 . Here we report a longitudinal thermal brightness map of the nearby transiting super-Earth 55 Cancri e (refs 4 , 5 ) revealing highly asymmetric dayside thermal emission and a strong day–night temperature contrast. Dedicated space-based monitoring of the planet in the infrared revealed a modulation of the thermal flux as 55 Cancri e revolves around its star in a tidally locked configuration. These observations reveal a hot spot that is located 41 ± 12 degrees east of the substellar point (the point at which incident light from the star is perpendicular to the surface of the planet). From the orbital phase curve, we also constrain the nightside brightness temperature of the planet to 1,380 ± 400 kelvin and the temperature of the warmest hemisphere (centred on the hot spot) to be about 1,300 kelvin hotter (2,700 ± 270 kelvin) at a wavelength of 4.5 micrometres, which indicates inefficient heat redistribution from the dayside to the nightside. Our observations are consistent with either an optically thick atmosphere with heat recirculation confined to the planetary dayside, or a planet devoid of atmosphere with low-viscosity magma flows at the surface 6 .

Seven rocky planets orbit the nearby dwarf star TRAPPIST-1, providing a unique opportunity to search for atmospheres on small planets outside the Solar System 1 . Thanks to the recent launch of the James Webb Space Telescope (JWST), possible atmospheric constituents such as carbon dioxide (CO 2 ) are now detectable 2 , 3 . Recent JWST observations of the innermost planet TRAPPIST-1 b showed that it is most probably a bare rock without any CO 2 in its atmosphere 4 . Here we report the detection of thermal emission from the dayside of TRAPPIST-1 c with the Mid-Infrared Instrument (MIRI) on JWST at 15 µm. We measure a planet-to-star flux ratio of f p / f ⁎  = 421 ± 94 parts per million (ppm), which corresponds to an inferred dayside brightness temperature of 380 ± 31 K. This high dayside temperature disfavours a thick, CO 2 -rich atmosphere on the planet. The data rule out cloud-free O 2 /CO 2 mixtures with surface pressures ranging from 10 bar (with 10 ppm CO 2 ) to 0.1 bar (pure CO 2 ). A Venus-analogue atmosphere with sulfuric acid clouds is also disfavoured at 2.6 σ confidence. Thinner atmospheres or bare-rock surfaces are consistent with our measured planet-to-star flux ratio. The absence of a thick, CO 2 -rich atmosphere on TRAPPIST-1 c suggests a relatively volatile-poor formation history, with less than 9.5 − 2.3 + 7.5 Earth oceans of water. If all planets in the system formed in the same way, this would indicate a limited reservoir of volatiles for the potentially habitable planets in the system. The detection of thermal emission from the rocky exoplanet TRAPPIST-1 c using the Mid-Infrared Instrument on the James Webb Space Telescope reveals a dayside brightness temperature that disfavours a thick, CO 2 -rich atmosphere.

Two exoplanet atmospheres examined This paper reports Hubble Space Telescope observations of the inner two of three Earth-sized exoplanets that were recently discovered close to the habitable zone of the nearby ultracool dwarf star TRAPPIST-1. The combined transmission spectrum of TRAPPIST-1 b and c was obtained during their simultaneous transits on 4 May 2016. The lack of features in the combined spectrum effectively rules out cloud-free hydrogen-dominated atmospheres for each planet, but they could have a variety of other types of atmosphere, from one consisting mainly of cloud-free water vapour to a Venus-like atmosphere. Three Earth-sized exoplanets were recently discovered close to the habitable zone 1 , 2 of the nearby ultracool dwarf star TRAPPIST-1 (ref. 3 ). The nature of these planets has yet to be determined, as their masses remain unmeasured and no observational constraint is available for the planetary population surrounding ultracool dwarfs, of which the TRAPPIST-1 planets are the first transiting example. Theoretical predictions span the entire atmospheric range, from depleted to extended hydrogen-dominated atmospheres 4 , 5 , 6 , 7 , 8 . Here we report observations of the combined transmission spectrum of the two inner planets during their simultaneous transits on 4 May 2016. The lack of features in the combined spectrum rules out cloud-free hydrogen-dominated atmospheres for each planet at ≥10 σ levels; TRAPPIST-1 b and c are therefore unlikely to have an extended gas envelope as they occupy a region of parameter space in which high-altitude cloud/haze formation is not expected to be significant for hydrogen-dominated atmospheres 9 . Many denser atmospheres remain consistent with the featureless transmission spectrum—from a cloud-free water-vapour atmosphere to a Venus-like one.

We report initial observations aimed at the characterization of a third interstellar object. This object, 3I/ATLAS or C/2025 N1 (ATLAS), was discovered on 2025 July 1 UT and has an orbital eccentricity of e ∼ 6.1, perihelion of q ∼ 1.36 au, inclination of ∼175°, and hyperbolic velocity of V∞ ∼ 58 km s−1. We report deep stacked images obtained using the Canada–France–Hawaii Telescope and the Very Large Telescope that resolve a compact coma. Using images obtained from several smaller ground-based telescopes, we find minimal light-curve variation for the object over a ∼4 day time span. The visible/near-infrared spectral slope of the object is 17.1% ± 0.2%/100 nm, comparable to other interstellar objects and primitive solar system small bodies (comets and D-type asteroids). Moreover, 3I/ATLAS will be observable through early 2025 September, then unobservable by Earth-based observatories near perihelion due to low solar elongation. It will be observable again from the ground in late 2025 November. Although this limitation unfortunately prohibits detailed Earth-based observations at perihelion when the activity of 3I/ATLAS is likely to peak, spacecraft at Mars could be used to make valuable observations at this time.

SPECULOOS is a ground-based transit survey consisting of six identical 1 m robotic telescopes. The immediate goal of the project is to detect temperate terrestrial planets transiting nearby ultracool dwarfs (late M-dwarf stars and brown dwarfs), which could be amenable for atmospheric research with the next generation of telescopes. Here, we report the developments of the northern counterpart of the project—SPECULOOS Northern Observatory, and present its performance during the first three years of operations from mid-2019 to mid-2022. Currently, the observatory consists of one telescope, which is named Artemis. The Artemis telescope demonstrates remarkable photometric precision, allowing it to be ready to detect new transiting terrestrial exoplanets around ultracool dwarfs. Over the period of the first three years after the installation, we observed 96 objects from the SPECULOOS target list for 6000 hr with a typical photometric precision of 0.5%, and reaching a precision of 0.2% for relatively bright non-variable targets with a typical exposure time of 25 s. Our weather downtime (clouds, high wind speed, high humidity, precipitation and/or high concentration of dust particles in the air) over the period of three years was 30% of overall night time. Our actual downtime is 40% because of additional time loss associated with technical problems.

A comprehensive infrared spectroscopic study of star TRAPPIST-1 is a crucial step toward the detailed examination of its planets. While the presence of Earth’s atmosphere has limited the spectral extent of such a study up to now, the Near Infrared Imager and Slitless Spectrograph (NIRISS) and the Near Infrared Spectrograph instruments aboard the James Webb Space Telescope (JWST) can now yield the 0.6–5 μm spectral energy distribution (SED) of the star. Here we translate TRAPPIST-1's SED into tight constraints on its luminosity (L bol = 0.000566 ± 0.000022 L ⊙), effective temperature (T eff = 2569 ± 28 K), and metallicity ([Fe/H] = 0.052 ± 0.073) and investigate the behavior of its gravity-sensitive indices. Through band-by-band comparisons of the NIRISS and ground-based spectra, TRAPPIST-1 exhibits a blend of both field source and intermediate-gravity spectral characteristics, suggesting that the star is likely a field-age source with spectral features reminiscent of young objects. We also employ photospheric modeling incorporating theoretical and JWST spectra to constrain stellar surface heterogeneities, finding that the limited fidelity of current stellar spectral models precludes definitive constraints on the physical parameters of the distinct spectral components giving rise to TRAPPIST-1's photospheric heterogeneity and variability. In addition, we find intermodel differences in the inferences of properties (e.g., the effective temperature) over one order of magnitude larger than the instrument-driven uncertainties (∼100 K vs. ∼4 K), pointing toward a model-driven accuracy wall. Our findings call for a new generation of stellar models to support the optimal mining of JWST data and further constraining stellar—and ultimately planetary—properties.

Dopamine agonist withdrawal syndrome (DAWS) is a severe condition reported primarily in Parkinson's disease (PD) but increasingly recognized in restless legs syndrome (RLS). While DAWS is classically associated with high-dose dopamine agonists (DAs) in Parkinson's disease, it has also been reported in RLS patients treated with low-dose therapy (≤ 0.75 mg pramipexole equivalent), although such cases remain rare. While direct evidence is lacking, psychological and relational stressors, in conjunction with prior medication adjustments, could plausibly modulate DAWS severity through a mechanism akin to kindling. We describe the case of a 51-year-old male who developed severe DAWS after withdrawing from low-dose pramipexole (0.26 mg) prescribed for RLS. A 6-month venlafaxine taper, completed 2 weeks before DA tapering, may have increased neurochemical vulnerability. Initial dose reduction caused akathisia, tremors, panic attacks, RLS worsening, and depressive symptoms. After brief reinstatement, abrupt cessation triggered painful electric-like sensations in the lower back and emotional collapse. The patient was transitioned to rotigotine (2 mg/day), together with other psychotropic medications, which provided partial and temporary relief. Symptoms relapsed during tapering, with marked worsening occurring in parallel with episodes of severe relational stress within a close personal connection. Clinical assessments explored these interactions as potential psychological stressors, as reported by the patient. Given the temporal association between these stressors and symptom relapses, relational factors may have contributed to the severity and recurrence of DAWS episodes. At 13 months after complete DA discontinuation, the patient has regained nearly full functionality, although episodes of marked fatigue and significant bedtime RLS persists. This case illustrates that DAWS can occur in RLS patients even at low DA doses, with atypical symptoms possibly involving autonomic and central sensitization. Relational stress may significantly exacerbate symptom severity, potentially leading to profound neurological destabilization through mechanisms such as cross-system hypersensitivity or a kindling-like process, as suggested by existing literature. This factor may need to be systematically assessed in DAWS management. As a rare patient-authored account, this report contributes to the understanding of DAWS in non-PD populations and highlights the need for longitudinal research to guide safer withdrawal protocols and integrated care.

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 present a near-infrared spectroscopic analysis (0.9–2.4 μm) of gravity indices for 56 ultracool dwarfs (M5.5–L0), including exoplanet hosts SPECULOOS-2, SPECULOOS-3, and LHS 3154. Our dataset includes 59 spectra from the SpeX and FIRE spectrographs. We also discuss literature results for TRAPPIST-1. Using gravity-sensitive spectral indices, including FeH absorption (0.99, 1.20, and 1.55 μm), the VO band at 1.06 μm, the H-band continuum, and alkali lines such as K I (1.17 and 1.25 μm), we investigate correlations between gravity classification, stellar metallicity, and the presence of close-in transiting planets. All four planet-hosting stars exhibit intermediate-gravity spectral signatures, despite indicators of field age. However, a volume-corrected logistic regression reveals no significant association between gravity class and planet occurrence. Among individual indices, we find FeHz to be the most promising tracer of planet-hosting status. We tentatively identify a correlation between FeHz (0.99 μm) and planet presence at the 2σ level, though the result may reflect observational biases, including transit probability, small-number statistics, and detection sensitivity. More robustly, we find a significant anticorrelation between FeHz and [Fe/H] (3.3σ). A Kruskal–Wallis test shows no significant [Fe/H] difference across gravity classes, suggesting the observed FeHz–[Fe/H] trend is not driven by bulk metallicity differences. We propose this anticorrelation may reflect the interplay between age, gravity, and composition: higher-metallicity objects may be systematically younger and have lower gravities, suppressing FeH absorption. While our results only hint at a link between gravity-related characteristics and planet occurrence among late-M dwarfs, they underscore the need for caution when using spectral diagnostics to infer the properties of planet-hosting ultracool dwarfs.