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Brown dwarfs serve as ideal laboratories for studying the atmospheres of giant exoplanets on wide orbits, as the governing physical and chemical processes within them are nearly identical 1 , 2 . Understanding the formation of gas-giant planets is challenging, often involving the endeavour to link atmospheric abundance ratios, such as the carbon-to-oxygen (C/O) ratio, to formation scenarios 3 . However, the complexity of planet formation requires further tracers, as the unambiguous interpretation of the measured C/O ratio is fraught with complexity 4 . Isotope ratios, such as deuterium to hydrogen and 14 N/ 15 N, offer a promising avenue to gain further insight into this formation process, mirroring their use within the Solar System 5 – 7 . For exoplanets, only a handful of constraints on 12 C/ 13 C exist, pointing to the accretion of 13 C-rich ice from beyond the CO iceline of the disks 8 , 9 . Here we report on the mid-infrared detection of the 14 NH 3 and 15 NH 3 isotopologues in the atmosphere of a cool brown dwarf with an effective temperature of 380 K in a spectrum taken with the Mid-Infrared Instrument (MIRI) of JWST. As expected, our results reveal a 14 N/ 15 N value consistent with star-like formation by gravitational collapse, demonstrating that this ratio can be accurately constrained. Because young stars and their planets should be more strongly enriched in the 15 N isotope 10 , we expect that 15 NH 3 will be detectable in several cold, wide-separation exoplanets. Observations from the JWST MIRI showed the detection of 14 NH 3 and 15 NH 3 isotopologues in the atmosphere of a cool brown dwarf, along with a 14 N/ 15 N value consistent with star-like formation by gravitational collapse.

Brown dwarfs serve as ideal laboratories for studying the atmospheres of giant exoplanets on wide orbits, as the governing physical and chemical processes within them are nearly identical . Understanding the formation of gas-giant planets is challenging, often involving the endeavour to link atmospheric abundance ratios, such as the carbon-to-oxygen (C/O) ratio, to formation scenarios . However, the complexity of planet formation requires further tracers, as the unambiguous interpretation of the measured C/O ratio is fraught with complexity . Isotope ratios, such as deuterium to hydrogen and N/ N, offer a promising avenue to gain further insight into this formation process, mirroring their use within the Solar System . For exoplanets, only a handful of constraints on C/ C exist, pointing to the accretion of C-rich ice from beyond the CO iceline of the disks . Here we report on the mid-infrared detection of the NH and NH isotopologues in the atmosphere of a cool brown dwarf with an effective temperature of 380 K in a spectrum taken with the Mid-Infrared Instrument (MIRI) of JWST. As expected, our results reveal a N/ N value consistent with star-like formation by gravitational collapse, demonstrating that this ratio can be accurately constrained. Because young stars and their planets should be more strongly enriched in the N isotope , we expect that NH will be detectable in several cold, wide-separation exoplanets.

WASP-107b is a warm (approximately 740 K) transiting planet with a Neptune-like mass of roughly 30.5  M ⊕ and Jupiter-like radius of about 0.94  R J (refs.  1 , 2 ), whose extended atmosphere is eroding 3 . Previous observations showed evidence for water vapour and a thick, high-altitude condensate layer in the atmosphere of WASP-107b (refs.  4 , 5 ). Recently, photochemically produced sulfur dioxide (SO 2 ) was detected in the atmosphere of a hot (about 1,200 K) Saturn-mass planet from transmission spectroscopy near 4.05 μm (refs.  6 , 7 ), but for temperatures below about 1,000 K, sulfur is predicted to preferably form sulfur allotropes instead of SO 2 (refs.  8 – 10 ). Here we report the 9 σ detection of two fundamental vibration bands of SO 2 , at 7.35 μm and 8.69 μm, in the transmission spectrum of WASP-107b using the Mid-Infrared Instrument (MIRI) of JWST. This discovery establishes WASP-107b as the second irradiated exoplanet with confirmed photochemistry, extending the temperature range of exoplanets exhibiting detected photochemistry from about 1,200 K down to about 740 K. Furthermore, our spectral analysis reveals the presence of silicate clouds, which are strongly favoured (around 7 σ ) over simpler cloud set-ups. Furthermore, water is detected (around 12 σ ) but methane is not. These findings provide evidence of disequilibrium chemistry and indicate a dynamically active atmosphere with a super-solar metallicity. The JWST MIRI transmission spectrum of WASP-107b, a transiting planet with Neptune-like mass and Jupiter-like radius, shows observations of sulfur dioxide and silicate clouds but no methane in its atmosphere, providing evidence of disequilibrium chemistry and active photochemistry.

We present a multifrequency far-field beam map for the 5-m dish telescope at the Bleien Observatory measured using a commercially available drone. We describe the hexacopter drone used in this experiment, the design of the flight pattern, and the data analysis scheme. This is the first application of this calibration method to a single-dish radio telescope in the far-field. The high signal-to-noise ratio data allows us to characterize the beam pattern with high accuracy out to at least the fourth side-lobe. The resulting two-dimensional beam pattern is compared with that derived from a more traditional calibration approach using an astronomical calibration source. We discuss the advantages of this method compared to other beam calibration methods. Our results show that this drone-based technique is very promising for ongoing and future radio experiments, where the knowledge of the beam pattern is key to obtaining high-accuracy cosmological and astronomical measurements.

Some planetary systems harbour debris disks containing planetesimals such as asteroids and comets. Collisions between such bodies produce small dust particles, the spectral features of which reveal their composition and, hence, that of their parent bodies. A measurement of the composition of olivine crystals (Mg2−2xFe2xSiO4) has been done for the protoplanetary disk HD 100546 and for olivine crystals in the warm inner parts of planetary systems. The latter compares well with the iron-rich olivine in asteroids (x ≈ 0.29). In the cold outskirts of the β Pictoris system, an analogue to the young Solar System, olivine crystals were detected but their composition remained undetermined, leaving unknown how the composition of the bulk of Solar System cometary olivine grains compares with that of extrasolar comets. Here we report the detection of the 69-micrometre-wavelength band of olivine crystals in the spectrum of β Pictoris. Because the disk is optically thin, we can associate the crystals with an extrasolar proto-Kuiper belt a distance of 15–45 astronomical units from the star (one astronomical unit is the Sun–Earth distance), determine their magnesium-rich composition (x = 0.01 ± 0.001) and show that they make up 3.6 ± 1.0 per cent of the total dust mass. These values are strikingly similar to those for the dust emitted by the most primitive comets in the Solar System, even though β Pictoris is more massive and more luminous and has a different planetary system architecture.

WASP-107b is a warm (approximately 740 K) transiting planet with a Neptune-like mass of roughly 30.5 M and Jupiter-like radius of about 0.94 R (refs.  ), whose extended atmosphere is eroding . Previous observations showed evidence for water vapour and a thick, high-altitude condensate layer in the atmosphere of WASP-107b (refs.  ). Recently, photochemically produced sulfur dioxide (SO ) was detected in the atmosphere of a hot (about 1,200 K) Saturn-mass planet from transmission spectroscopy near 4.05 μm (refs.  ), but for temperatures below about 1,000 K, sulfur is predicted to preferably form sulfur allotropes instead of SO (refs.  ). Here we report the 9σ detection of two fundamental vibration bands of SO , at 7.35 μm and 8.69 μm, in the transmission spectrum of WASP-107b using the Mid-Infrared Instrument (MIRI) of JWST. This discovery establishes WASP-107b as the second irradiated exoplanet with confirmed photochemistry, extending the temperature range of exoplanets exhibiting detected photochemistry from about 1,200 K down to about 740 K. Furthermore, our spectral analysis reveals the presence of silicate clouds, which are strongly favoured (around 7σ) over simpler cloud set-ups. Furthermore, water is detected (around 12σ) but methane is not. These findings provide evidence of disequilibrium chemistry and indicate a dynamically active atmosphere with a super-solar metallicity.

We describe the operations concept and data reduction plan for the Mid-Infrared Instrument (MIRI) for the James Webb Space Telescope (JWST). The overall JWST operations concept is to use observation templates (OTs) to provide a straightforward and intuitive way for users to specify observations. MIRI has four OTs that correspond to the four observing modes: (1) imaging, (2) coronagraphy, (3) low-resolution spectroscopy, and (4) medium-resolution spectroscopy. We outline the user choices and expansion of these choices into detailed instrument operations. The data reduction plans for MIRI are split into three stages, where the specificity of the reduction steps to the observation type increases with stage. The reduction starts with integration ramps: stage 1 yields uncalibrated slope images; stage 2 calibrates the slope images; and then stage 3 combines multiple calibrated slope images into high-level data products (e.g., mosaics, spectral cubes, and extracted source information). Finally, we give examples of the data and data products that will be derived from each of the four different OTs.

The first JWST/MIRI photometric observations of TRAPPIST-1 b allowed for the detection of the thermal emission of the planet at 15 µm, suggesting that the planet could be a bare rock with a zero albedo and no redistribution of heat. These observations at 15 µm were acquired as part of GTO time that included a twin program at 12.8 µm in order to have a measurement in and outside the CO 2 absorption band. Here we present five new occultations of TRAPPIST-1 b observed with MIRI in an additional photometric band at 12.8 µm. We perform a global fit of the 10 eclipses and derive a planet-to-star flux ratio and 1-σ error of 452 ± 86 ppm and 775 ± 90 ppm at 12.8 µm and 15 µm, respectively. We find that two main scenarios emerge. An airless planet model with an unweathered (fresh) ultramafic surface, that could be indicative of relatively recent geological processes fits well the data. Alternatively, a thick, pure-CO2 atmosphere with photochemical hazes that create a temperature inversion and result in the CO2 feature being seen in emission also works, although with some caveats. Our results highlight the challenges in accurately determining a planet's atmospheric or surface nature solely from broadband filter measurements of its emission, but also point towards two very interesting scenarios that will be further investigated with the forthcoming phase curve of TRAPPIST-1 b.

MIRI/MRS on board the JWST allows us to probe the inner regions of protoplanetary disks. Here we examine the disk around the classical T Tauri star Sz 98, which has an unusually large dust disk in the millimetre with a compact core. We focus on the H\\(_2\\)O emission through both its ro-vibrational and pure rotational emission. Furthermore, we compare our chemical findings with those obtained for the outer disk from Atacama Large Millimeter/submillimeter Array (ALMA) observations. In order to model the molecular features in the spectrum, the continuum was subtracted and LTE slab models were fitted. The spectrum was divided into different wavelength regions corresponding to H\\(_2\\)O lines of different excitation conditions, and the slab model fits were performed individually per region. We confidently detect CO, H\\(_2\\)O, OH, CO\\(_2\\), and HCN in the emitting layers. The isotopologue H\\(^{18}_2\\)O is not detected. Additionally, no other organics, including C\\(_2\\)H\\(_2\\), are detected. This indicates that the C/O ratio could be substantially below unity, in contrast with the outer disk. The H\\(_2\\)O emission traces a large radial disk surface region, as evidenced by the gradually changing excitation temperatures and emitting radii. The OH and CO\\(_2\\) emission are relatively weak. It is likely that H\\(_2\\)O is not significantly photodissociated; either due to self-shielding against the stellar irradiation, or UV-shielding from small dust particles. The relative emitting strength of the different identified molecular features point towards UV-shielding of H\\(_2\\)O in the inner disk of Sz 98, with a thin layer of OH on top. The majority of the organic molecules are either hidden below the dust continuum, or not present. In general, the inferred composition points to a sub-solar C/O ratio (<0.5) in the inner disk, in contrast with the larger than unity C/O ratio in the gas in the outer disk found with ALMA.

With the advent of JWST, we acquire unprecedented insights into the physical and chemical structure of the inner regions of planet-forming disks where terrestrial planet formation occurs. The very low-mass stars (VLMS) are known to have a high occurrence rate of the terrestrial planets around them. Exploring the chemical composition of the gas in these inner regions of the disks can aid a better understanding of the connection between planet-forming disks and planets. The MIRI mid-Infrared Disk Survey (MINDS) project is a large JWST Guaranteed Time program to characterize the chemistry and physical state of planet-forming and debris disks. We use the JWST-MIRI/MRS spectrum to investigate the gas and dust composition of the planet-forming disk around the very low-mass star Sz28 (M5.5, 0.12\\,M\\(_{\\odot}\\)). We use the dust-fitting tool (DuCK) to determine the dust continuum and to get constraints on the dust composition and grain sizes. We use 0D slab models to identify and fit the molecular spectral features, yielding estimates on the temperature, column density and the emitting area. To test our understanding of the chemistry in the disks around VLMS, we employ the thermo-chemical disk model {P{\\tiny RO}D{\\tiny I}M{\\tiny O}} and investigate the reservoirs of the detected hydrocarbons. We explore how the C/O ratio affects the inner disk chemistry. JWST reveals a plethora of hydrocarbons, including \\ce{CH3}, \\ce{CH4}, \\ce{C2H2}, \\ce{^{13}CCH2}, \\ce{C2H6}, \\ce{C3H4}, \\ce{C4H2} and \\ce{C6H6} suggesting a disk with a gaseous C/O\\,>\\,1. Additionally, we detect \\ce{CO2}, \\ce{^{13}CO2}, \\ce{HCN}, and \\ce{HC3N}. \\ce{H2O} and OH are absent in the spectrum. We do not detect PAHs. Photospheric stellar absorption lines of \\ce{H2O} and \\ce{CO} are identified. Notably, our radiation thermo-chemical disk models are able to produce these detected hydrocarbons in the surface layers of the disk when the ...