Measuring the abundances of carbon and oxygen in exoplanet atmospheres is considered a crucial avenue for unlocking the formation and evolution of exoplanetary systems(1,2). Access to the chemical inventory of an exoplanet requires high-precision observations, often inferred from individual molecular detections with low-resolution space-based(3-5) and high-resolution ground-based(6-8) facilities. Here we report the medium-resolution (R & AP; 600) transmission spectrum of an exoplanet atmosphere between 3 and 5 mu m covering several absorption features for the Saturn-mass exoplanet WASP-39b (ref. (9)), obtained with the Near Infrared Spectrograph (NIRSpec) G395H grating of JWST. Our observations achieve 1.46 times photon precision, providing an average transit depth uncertainty of 221 ppm per spectroscopic bin, and present minimal impacts from systematic effects. We detect significant absorption from CO2 (28.5 sigma) and H2O (21.5 sigma), and identify SO2 as the source of absorption at 4.1 mu m (4.8 sigma). Best-fit atmospheric models range between 3 and 10 times solar metallicity, with sub-solar to solar C/O ratios. These results, including the detection of SO2, underscore the importance of characterizing the chemistry in exoplanet atmospheres and showcase NIRSpec G395H as an excellent mode for time-series observations over this critical wavelength range(10).

Close-in giant exoplanets with temperatures greater than 2,000K ('ultra-hot Jupiters') have been the subject of extensive efforts to determine their atmospheric properties using thermal emission measurements from the Hubble Space Telescope (HST) and Spitzer Space Telescope1-3. However, previous studies have yielded inconsistent results because the small sizes of the spectral features and the limited information content of the data resulted in high sensitivity to the varying assumptions made in the treatment of instrument systematics and the atmosphericretrieval analysis3-12. Here we present a dayside thermal emission spectrum of the ultra-hot Jupiter WASP-18b obtained with the NIRISS13 instrument on the JWST. The data span 0.85 to 2.85mum in wavelength at an average resolving power of 400 and exhibit minimal systematics. The spectrum shows three wateremission features (at >6sigma confidence) and evidence for optical opacity, possiblyattributable to H-, TiO and VO (combined significance of 3.8sigma). Models that fit the data require a thermal inversion, molecular dissociation as predicted by chemical equilibrium, a solar heavy-element abundance ('metallicity', [Formula: see text] times solar) and a carbon-to-oxygen (C/O) ratio less than unity. The data also yield a dayside brightness temperature map, which shows a peak in temperature near the substellar point that decreases steeply and symmetrically with longitude towards the terminators.

One of the frontiers for advancing what is known about dark matter lies in using strong gravitational lenses to characterize the population of the smallest dark matter haloes. There is a large volume of information in strong gravitational lens images - the question we seek to answer is to what extent we can refine this information. To this end, we forecast the detectability of a mixed warm and cold dark matter scenario using the anomalous flux ratio method from strong gravitational lensed images. The halo mass function of the mixed dark matter scenario is suppressed relative to cold dark matter but still predicts numerous low-mass dark matter haloes relative to warm dark matter. Since the strong lensing signal receives a contribution from a range of dark matter halo masses and since the signal is sensitive to the specific configuration of dark matter haloes, not just the halo mass function, degeneracies between different forms of suppression in the halo mass function, relative to cold dark matter, can arise. We find that, with a set of lenses with different configurations of the main deflector and hence different sensitivities to different mass ranges of the halo mass function, the different forms of suppression of the halo mass function between the warm dark matter model and the mixed dark matter model can be distinguished with 40 lenses with Bayesian odds of 30:1.

Distinguishing deep lower mantle heterogeneities and resolving their physical and chemical properties are challenging due to the difficulty in achieving severe high-temperature and high-pressure conditions simultaneously in mineral experiments. Deep-seated mantle plumes bring these heterogeneities to the Earth's surface, therefore providing a unique insight into the Earth's deep interior. Here, we link the surface temperature fluctuation of mantle plume to the properties of deep-mantle heterogeneities via three-dimensional geodynamic modeling. Our results show that high-viscosity primordial mantle materials significantly increase the surface plume temperature due to their excessive viscous heating, whereas high-density oceanic crust slightly reduces it. Give some estimates for the maximum plume fluctuation temperature through time, the survival of scattered primordial blobs with a high viscosity contrast of -10-50 times in the deep-mantle reservoir is required. The temperature variations of the thermochemical mantle plume likely control the observed multiple volcanic episodes of large igneous provinces and periodic changes of volcanic flux along hotspot tracks.& COPY; 2023 Elsevier B.V. All rights reserved.

Photochemistry is a fundamental process of planetary atmospheres that regulates the atmospheric composition and stability(1). However, no unambiguous photochemical products have been detected in exoplanet atmospheres so far. Recent observations from the JWST Transiting Exoplanet Community Early Release Science Program(2,3) found a spectral absorption feature at 4.05 mu m arising from sulfur dioxide (SO2) in the atmosphere of WASP-39b. WASP-39b is a 1.27-Jupiter-radii, Saturn-mass (0.28 M-J) gas giant exoplanet orbiting a Sun-like star with an equilibrium temperature of around 1,100 K (ref. (4)). The most plausible way of generating SO2 in such an atmosphere is through photochemical processes(5,6). Here we show that the SO2 distribution computed by a suite of photochemical models robustly explains the 4.05-mu m spectral feature identified by JWST transmission observations(7) with NIRSpec PRISM (2.7s)(8) and G395H (4.5s)(9). SO2 is produced by successive oxidation of sulfur radicals freed when hydrogen sulfide (H2S) is destroyed. The sensitivity of the SO2 feature to the enrichment of the atmosphere by heavy elements (metallicity) suggests that it can be used as a tracer of atmospheric properties, with WASP-39b exhibiting an inferred metallicity of about 10x solar. We further point out that SO2 also shows observable features at ultraviolet and thermal infrared wavelengths not available from the existing observations.

Photoevaporation is a potential explanation for several features within exoplanet demographics. Atmospheric escape observed in young Neptune-sized exoplanets can provide insight into and characterize which mechanisms drive this evolution and at what times they dominate. AU Mic b is one such exoplanet, slightly larger than Neptune (4.19 R (& OPLUS;)). It closely orbits a 23 Myr pre-main-sequence M dwarf with an orbital period of 8.46 days. We obtained two visits of AU Mic b at Ly & alpha; with Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph. One flare within the first HST visit is characterized and removed from our search for a planetary transit. We present a nondetection in our first visit, followed by the detection of escaping neutral hydrogen ahead of the planet in our second visit. The outflow absorbed & SIM;30% of the star's Ly & alpha; blue wing 2.5 hr before the planet's white-light transit. We estimate that the highest-velocity escaping material has a column density of 10(13.96) cm(-2) and is moving 61.26 km s(-1) away from the host star. AU Mic b's large high-energy irradiation could photoionize its escaping neutral hydrogen in 44 minutes, rendering it temporarily unobservable. Our time-variable Ly & alpha; transit ahead of AU Mic b could also be explained by an intermediate stellar wind strength from AU Mic that shapes the escaping material into a leading tail. Future Ly & alpha; observations of this system will confirm and characterize the unique variable nature of its Ly & alpha; transit, which, combined with modeling, will tune the importance of stellar wind and photoionization.

Stishovite is a key mineral for understanding the deep Earth water cycle because of its potential as a main carrier for water into the transition zone and lower mantle. During subduction-related metamorphism of basaltic oceanic crust, stishovite stabilizes at 8-9 GPa and comprises 10-25 vol% of the bulk mineralogy, with some experimental studies indicating that stishovite can accommodate 3.5 wt% H2O or more in the transition zone and upper lower mantle. This large water solubility has been explained by a hydrogarnet substitution mechanism (1Si(4+) & LRARR; 4H(+)) and/or the incorporation of interstitial molecular water. To investigate water speciation and hydrogen isotope behavior, we synthesized partially deuterated hydrous stishovite at 9 GPa and 450 & DEG;C in a multi-anvil press (MA). The hydrous stishovite contains on average 1.69 & PLUSMN; 0.05 wt% water, which is consistent with earlier MA studies but is significantly lower than the 3.5 wt% reported from in situ diamond anvil cell (DAC) studies made at higher pressures and temperatures. H-1 MAS NMR spinning sideband characteristics suggest a high abundance of interstitial molecular water in hydrous stishovite, while the presence of a hydrogarnet defect cannot be ruled out. Unit-cell volumes and deuterium enrichment in the quenched hydrous stishovite indicate that similar to 45% of the water is lost from the stishovite upon quenching and decompression of the experiment, consistent with a higher solubility. This implies that the pristine water contents of a P-T-fO(2) equilibrated hydrous stishovite cannot be quenched to 1 atm and room temperature from classical MA experiments. We further present a capillary-based recovery method for fluid from experimental capsules, allowing direct determination of the D/H ratio of the experimental fluid and indirect determination of the hydrous stishovite. Using Rayleigh modeling to account for the quench-related water loss, we find that, at 450 & DEG;C and 9 GPa, deuterium is 3.5-4.5 times enriched in hydrous stishovite relative to coexisting aqueous fluid. This is opposite of what is commonly observed for mineral-fluid pairs above 300 & DEG;C, rendering hydrous stishovite a potential sink for deuterium and decreasing the D/H ratio of coexisting aqueous fluids. Partial decomposition (30-60%) of hydrous stishovite during mantle upwelling and production of primary basaltic melts could be accompanied by high-temperature D/H fractionation, decreasing the hydrogen isotope composition of such melts towards "mantle-like" delta D values between -75 and -220 parts per thousand.

Simple Summary The success of coral reefs is underpinned by the symbiosis between corals and their dinoflagellate symbionts. Crucially, metabolic interactions between the two partners support coral metabolism and survival, although these can be influenced by symbiont identity and inter-partner compatibility. Here, we measured how symbiont identity influences the release of biogenic volatile organic compounds (BVOCs) via the symbiosis, and related this to concurrent shifts in the host microbiome; BVOCs are end-products of metabolism and important biological signal molecules. We used the sea anemone Aiptasia, a model system for cnidarian-dinoflagellate symbiosis, when either symbiont-free, populated with its native symbiont, or populated with a non-native symbiont. We detected 142 BVOCs across all treatments. The volatile profiles of symbiont-free anemones and those containing the native symbiont were distinct, while the volatile profile of anemones containing the non-native symbiont shared characteristics with both. The symbiotic state also caused a change in the host microbiome, but this did not explain the changes seen in BVOC release. These findings contribute to our understanding of how corals may respond to climate change should they acquire novel symbionts post-bleaching. Furthermore, we provide a platform for future studies of the metabolic and/or signalling roles of BVOCs in this important symbiosis. The symbiosis between cnidarians and dinoflagellates underpins the success of reef-building corals in otherwise nutrient-poor habitats. Alterations to symbiotic state can perturb metabolic homeostasis and thus alter the release of biogenic volatile organic compounds (BVOCs). While BVOCs can play important roles in metabolic regulation and signalling, how the symbiotic state affects BVOC output remains unexplored. We therefore characterised the suite of BVOCs that comprise the volatilome of the sea anemone Exaiptasia diaphana ('Aiptasia') when aposymbiotic and in symbiosis with either its native dinoflagellate symbiont Breviolum minutum or the non-native symbiont Durusdinium trenchii. In parallel, the bacterial community structure in these different symbiotic states was fully characterised to resolve the holobiont microbiome. Based on rRNA analyses, 147 unique amplicon sequence variants (ASVs) were observed across symbiotic states. Furthermore, the microbiomes were distinct across the different symbiotic states: bacteria in the family Vibrionaceae were the most abundant in aposymbiotic anemones; those in the family Crocinitomicaceae were the most abundant in anemones symbiotic with D. trenchii; and anemones symbiotic with B. minutum had the highest proportion of low-abundance ASVs. Across these different holobionts, 142 BVOCs were detected and classified into 17 groups based on their chemical structure, with BVOCs containing multiple functional groups being the most abundant. Isoprene was detected in higher abundance when anemones hosted their native symbiont, and dimethyl sulphide was detected in higher abundance in the volatilome of both Aiptasia-Symbiodiniaceae combinations relative to aposymbiotic anemones. The volatilomes of aposymbiotic anemones and anemones symbiotic with B. minutum were distinct, while the volatilome of anemones symbiotic with D. trenchii overlapped both of the others. Collectively, our results are consistent with previous reports that D.

Recent work has shown that evaluating functional trait distinctiveness, the average trait distance of a species to other species in a community offers promising insights into biodiversity dynamics and ecosystem functioning. However, the ecological mechanisms underlying the emergence and persistence of functionally distinct species are poorly understood. Here, we address the issue by considering a heterogeneous fitness landscape whereby functional dimensions encompass peaks representing trait combinations yielding positive population growth rates in a community. We identify four ecological cases contributing to the emergence and persistence of functionally distinct species. First, environmental heterogeneity or alternative phenotypic designs can drive positive population growth of functionally distinct species. Second, sink populations with negative population growth can deviate from local fitness peaks and be functionally distinct. Third, species found at the margin of the fitness landscape can persist but be functionally distinct. Fourth, biotic interactions (positive or negative) can dynamically alter the fitness landscape. We offer examples of these four cases and guidelines to distinguish between them. In addition to these deterministic processes, we explore how stochastic dispersal limitation can yield functional distinctiveness. Our framework offers a novel perspective on the relationship between fitness landscape heterogeneity and the functional composition of ecological assemblages.