4,175 research outputs found

    Nightside clouds and disequilibrium chemistry on the hot Jupiter WASP-43b

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    This is the author accepted manuscript.Data Availability: The data used in this paper are associated with JWST DD-ERS program 1366 (PIs Batalha, Bean, and Stevenson; observation 11) and are publicly available from the Mikulski Archive for Space Telescopes (https://mast.stsci.edu). Additional intermediate and final results from this work are archived on Zenodo at https://zenodo.org/doi/10.5281/zenodo.10525170Hot Jupiters are among the best-studied exoplanets, but it is still poorly understood how their chemical composition and cloud properties vary with longitude. Theoretical models predict that clouds may condense on the nightside and that molecular abundances can be driven out of equilibrium by zonal winds. Here we report a phase-resolved emission spectrum of the hot Jupiter WASP-43b measured from 5–12 µm with JWST’s Mid-Infrared Instrument (MIRI). The spectra reveal a large day–night temperature contrast (with average brightness temperatures of 1524 ± 35 and 863 ± 23 Kelvin, respectively) and evidence for water absorption at all orbital phases. Comparisons with three-dimensional atmospheric models show that both the phase curve shape and emission spectra strongly suggest the presence of nightside clouds which become optically thick to thermal emission at pressures greater than ∼100 mbar. The dayside is consistent with a cloudless atmosphere above the mid-infrared photosphere. Contrary to expectations from equilibrium chemistry but consistent with disequilibrium kinetics models, methane is not detected on the nightside (2σ upper limit of 1–6 parts per million, depending on model assumptions).NASAEuropean Research Council (ERC)NSFNHFP Sagan Fellowship ProgramAustrian Science Fund (FWF)Science and Technology Facilities Council (STFC)KU LeuvenEuropean Union Horizon 2020FWOANRCentre National d’Etudes Spatiales (CNES

    Final Results of GERDA on the Two-Neutrino Double-β\beta Decay Half-Life of 76^{76}Ge

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    We present the measurement of the two-neutrino double-β\beta decay rate of 76^{76}Ge performed with the GERDA Phase II experiment. With a subset of the entire GERDA exposure, 11.8 kg\cdotyr, the half-life of the process has been determined: T1/22ν=(2.022±0.018stat±0.038sys)×1021T^{2\nu}_{1/2} = (2.022 \pm 0.018_{stat} \pm 0.038_{sys})\times10^{21} yr. This is the most precise determination of the 76^{76}Ge two-neutrino double-β\beta decay half-life and one of the most precise measurements of a double-β\beta decay process. The relevant nuclear matrix element can be extracted: Meff2ν=(0.101±0.001).M^{2\nu}_{\text{eff}} = (0.101\pm0.001).Comment: 7 pages, 4 figures, 2 table