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Early Release Science of the exoplanet WASP-39b with JWST NIRSpec G395H.

Lili AldersonHannah R WakefordMunazza K AlamNatasha E BatalhaJoshua D LothringerJea Adams RedaiSaugata BaratJonathan BrandeMario DamianoTansu DaylanNéstor EspinozaLaura FlaggJayesh M GoyalDavid GrantRenyu HuJulie InglisElspeth K H LeeThomas Mikal-EvansLakeisha Ramos-RosadoPierre-Alexis RoyNicole L WallackNatalie M BatalhaJacob L BeanBjörn BennekeZachory K Berta-ThompsonAarynn L CarterQuentin ChangeatKnicole D ColónIan J M CrossfieldJean-Michel DésertDaniel Foreman-MackeyNeale P GibsonLaura KreidbergMichael R LineMercedes López-MoralesKaran MolaverdikhaniSarah E MoranGiuseppe MorelloJulianne I MosesSagnick MukherjeeEverett SchlawinDavid K SingKevin B StevensonJake TaylorKeshav AggarwalEva-Maria AhrerNatalie H AllenJoanna K BarstowTaylor J BellJasmina BlecicSarah L CasewellKaty L ChubbNicolas CrouzetPatricio E CubillosLeen DecinAdina D FeinsteinJoanthan J FortneyJoseph HarringtonKevin HengNicolas IroEliza M-R KemptonJames KirkHeather A KnutsonJessica KrickJérémy LeconteMonika LendlRyan J MacDonaldLuigi ManciniMegan MansfieldErin M MayNathan J MayneYamila MiguelNikolay K NikolovKazumasa OhnoEnric PalleVivien ParmentierDominique J M Petit Dit de la RocheCaroline PiauletDiana PowellBenjamin V RackhamSeth RedfieldLaura K RogersZafar RustamkulovXianyu TanP TremblinShang-Min TsaiJake D TurnerMiguel de Val-BorroOlivia VenotLuis WelbanksPeter J WheatleyXi Zhang
Published in: Nature (2023)
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 ≈ 600) transmission spectrum of an exoplanet atmosphere between 3 and 5 μm 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 CO 2 (28.5σ) and H 2 O (21.5σ), and identify SO 2 as the source of absorption at 4.1 μm (4.8σ). 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 SO 2 , 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 .
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