Publications by authors named "Jonathan Brande"

The recent inference of sulfur dioxide (SO) in the atmosphere of the hot (approximately 1,100 K), Saturn-mass exoplanet WASP-39b from near-infrared JWST observations suggests that photochemistry is a key process in high-temperature exoplanet atmospheres. This is because of the low (<1 ppb) abundance of SO under thermochemical equilibrium compared with that produced from the photochemistry of HO and HS (1-10 ppm). However, the SO inference was made from a single, small molecular feature in the transmission spectrum of WASP-39b at 4.

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Article Synopsis
  • Measuring the metallicity and carbon-to-oxygen (C/O) ratio in exoplanet atmospheres helps to understand their chemical processes and formation history.
  • The James Webb Space Telescope (JWST) allows for advanced observations of exoplanets, notably WASP-39b, providing insights through time-series data with high precision in a new wavelength range.
  • Findings include the detection of water vapor in the atmosphere with a high metallicity (1-100 times that of the Sun) and a low C/O ratio, suggesting the potential for significant solid material accretion during formation or chemical disequilibrium in the atmosphere.
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The Saturn-mass exoplanet WASP-39b has been the subject of extensive efforts to determine its atmospheric properties using transmission spectroscopy. However, these efforts have been hampered by modelling degeneracies between composition and cloud properties that are caused by limited data quality. Here we present the transmission spectrum of WASP-39b obtained using the Single-Object Slitless Spectroscopy (SOSS) mode of the Near Infrared Imager and Slitless Spectrograph (NIRISS) instrument on the JWST.

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Measuring the abundances of carbon and oxygen in exoplanet atmospheres is considered a crucial avenue for unlocking the formation and evolution of exoplanetary systems. Access to the chemical inventory of an exoplanet requires high-precision observations, often inferred from individual molecular detections with low-resolution space-based and high-resolution ground-based facilities. Here we report the medium-resolution (R ≈ 600) transmission spectrum of an exoplanet atmosphere between 3 and 5 μm covering several absorption features for the Saturn-mass exoplanet WASP-39b (ref.

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Background & Aims: Nutrition support is frequently indicated in patients with head and neck cancer (HNC). However, the optimal timing of enteral tube placement and feeding commencement is unknown. This review aims to compare the outcomes for patients with HNC undergoing curative intent radiotherapy (RT) or chemoradiotherapy (CRT) receiving either prophylactic percutaneous endoscopic gastrostomy (pPEG) tube placement/feeding or reactive enteral nutrition (rEN).

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