A precise metallicity and carbon-to-oxygen ratio for a warm giant exoplanet from its panchromatic JWST emission spectrum.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40982673.
- Also identified by DOI 10.1073/pnas.2416193122 and PMC identifier 12501160.
- Licence recorded as CC BY-NC-ND.
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Abstract
WASP-80 b, a warm sub-Jovian (equilibrium temperature [Formula: see text]820 K, 0.5 Jupiter masses), presents an opportunity to characterize a rare gas giant exoplanet around a low-mass star. In addition, its moderate temperature enables its atmosphere to host a range of carbon and oxygen species (H<sub>2</sub>O, CH<sub>4</sub>, CO, CO<sub>2</sub>, NH<sub>3</sub>). In this paper, we present a panchromatic emission spectrum of WASP-80 b, the first gas giant around a late K/early M-dwarf star and the coolest planet for which the James Webb Space Telescope has obtained a complete emission spectrum spanning 2.4 to 12 [Formula: see text]m, including NIRCam F322W2 (2.4 to 4 [Formula: see text]m) and F444W (4 to 5 [Formula: see text]m), and MIRI LRS (5 to 12 [Formula: see text]m). We report confident detections of H<sub>2</sub>O, CH<sub>4</sub>, CO, and CO<sub>2</sub>, and a tentative detection of NH<sub>3</sub>. We estimate WASP-80 b's atmospheric metallicity and carbon-to-oxygen ratio and compare them with estimates for other gas giants. Despite the relative rarity of giant planets around low-mass stars, we find that WASP-80 b's composition is consistent with other hot gas giants, suggesting that the formation pathway of WASP-80 b may not be dissimilar from hot gas giants around higher-mass stars.