Photochemically produced SO2 in the atmosphere of WASP-39b

S.-M.T. is supported by the European Research Council advanced grant EXOCONDENSE (no. 740963; principal investigator: R. T. Pierrehumbert). E.K.H.L. is supported by the SNSF Ambizione Fellowship grant (no. 193448). X.Z. is supported by NASA Exoplanet Research grant 80NSSC22K0236. O.V. acknowledges funding from the ANR project ‘EXACT’ (ANR-21-CE49-0008-01), from the Centre National d’Études Spatiales (CNES) and from the CNRS/INSU Programme National de Planétologie (PNP). L.D. acknowledges support from the European Union H2020-MSCA-ITN-2109 under grant no. 860470 (CHAMELEON) and the KU Leuven IDN/19/028 grant Escher. This work benefited from the 2022 Exoplanet Summer Program at the Other Worlds Laboratory (OWL) at the University of California, Santa Cruz, a programme financed by the Heising-Simons Foundation. T.D. is an LSSTC Catalyst Fellow. J.K. is an Imperial College Research Fellow. B.V.R. is a 51 Pegasi b Fellow. L.W. is an NHFP Sagan Fellow. A.D.F. is an NSF Graduate Research Fellow.Photochemistry is a fundamental process of planetary atmospheres that regulates the atmospheric composition and stability1. However, no unambiguous photochemical products have been detected in exoplanet atmospheres so far. Recent observations from the JWST Transiting Exoplanet Community Early Release Science Program2,3 found a spectral absorption feature at 4.05 μm arising from sulfur dioxide (SO2) in the atmosphere of WASP-39b. WASP-39b is a 1.27-Jupiter-radii, Saturn-mass (0.28 MJ) 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 processes5,6. Here we show that the SO2 distribution computed by a suite of photochemical models robustly explains the 4.05-μm spectral feature identified by JWST transmission observations7 with NIRSpec PRISM (2.7σ)8 and G395H (4.5σ)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 10× solar. We further point out that SO2 also shows observable features at ultraviolet and thermal infrared wavelengths not available from the existing observations.Publisher PDFPeer reviewe

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM

An active learning environment to improve first-year mechanical engineering retention rates and software skills

This work proposes a foundational change from traditional lecture to an active learning environment in the Colorado State University First-Year Introduction to Mechanical Engineering course of 145 students. The goal of this approach is to improve computational capabilities in Mechanical Engineering and long-term retention rates with a single broad emphasis. Major and minor changes were implemented in the course, from specific day to day in-class activities to the addition of laboratory sessions to replace traditional classroom lecture. These laboratories of no more than fifteen students were delivered by Learning Assistants, which were upper-level undergraduate peer educators. To evaluate proficiency, a MATLAB post-test was delivered to students who were instructed through lecture only ( Lecture ) and those who were instructed with the above changes ( Active ). A survey was also provided upon completion of the course to the Active group for student reflection on their perceived software capability and the usefulness of approaches. Post-test results suggest that the Active group was more proficient in MATLAB than the Lecture group. Survey results suggest that the Active group recognize they had not achieved expert use of the software but that they were likely to use it throughout their careers and that all approaches were useful, in particular the use of Learning Assistants. Future longterm retention statistics will shed light on the possible effectiveness of this approach, which are currently unavailable

Group for Assistance on the Storage of Grains in Africa

Meeting: Seminar on the Methodology of Evaluating Grain Storage Losses, 6-7 Feb. 1973, London, G

Improvement of an international research experience: Year two

Six students from The Ohio State University were sent to Jaipur, India during the summer of 2015 to conduct research on the Jaipur Foot, a low cost lower limb prosthesis. As a continuation of the research conducted by the first cohort, in the summer of 2016 four different students were sent to Jaipur to conduct research. However, based on the successes and difficulties from the 2015 year, a number of changes were instituted to improve both the educational and research goals for the student researchers. This paper will outline these changes, identify how they affected student learning and technical success, and make suggestions for further improvement in the final year of the program. One major change to the structure of the research experience program included employing a research component to an independent study course during the spring 2016 semester. This course focused on preparing students from not only a cultural standpoint, but also from a technical content specific to the project, including the use of material testing systems and finite element analysis. As students from two geographically dispersed institutions were selected for the research experience, they were encouraged to adapt to working with both Indian and American scientists whom they had not previously collaborated with. The targeted improvements made in the second year allowed for better technical preparation and further development of collaborative and teamwork skills. These goals are evaluated using a broad range of metrics, including student journals during the research experience in India and pre and post surveys focusing on technical and teamwork skills specific to global competency. Observations suggest that students were better prepared to conduct technical research as a result of the expanded independent study course and that the limited interaction between students prior to arrival had no negative impacts on teamwork. This study could be used to support project specific technical education and preparing a diverse team prior to conducting undergraduate international research programs