TY - JOUR
T1 - A precise metallicity and carbon-to-oxygen ratio for a warm giant exoplanet from its panchromatic JWST emission spectrum
AU - Wiser, Lindsey S.
AU - Bell, Taylor J.
AU - Line, Michael R.
AU - Schlawin, Everett
AU - Beatty, Thomas G.
AU - Welbanks, Luis
AU - Greene, Thomas P.
AU - Parmentier, Vivien
AU - Murphy, Matthew M.
AU - Fortney, Jonathan J.
AU - Arnold, Kenny
AU - Mehta, Nishil
AU - Ohno, Kazumasa
AU - Mukherjee, Sagnick
N1 - Publisher Copyright:
Copyright © 2025 the Author(s).
PY - 2025/9/30
Y1 - 2025/9/30
N2 - WASP-80 b, a warm sub-Jovian (equilibrium temperature ∼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 (H2O, CH4, CO, CO2, NH3). 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 μm, including NIRCam F322W2 (2.4 to 4 μm) and F444W (4 to 5 μm), and MIRI LRS (5 to 12 μm). We report confident detections of H2O, CH4, CO, and CO2, and a tentative detection of NH3. 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.
AB - WASP-80 b, a warm sub-Jovian (equilibrium temperature ∼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 (H2O, CH4, CO, CO2, NH3). 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 μm, including NIRCam F322W2 (2.4 to 4 μm) and F444W (4 to 5 μm), and MIRI LRS (5 to 12 μm). We report confident detections of H2O, CH4, CO, and CO2, and a tentative detection of NH3. 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.
KW - JWST
KW - WASP-80 b
KW - atmospheres
KW - exoplanets
KW - planet formation
UR - https://www.scopus.com/pages/publications/105016768577
UR - https://www.scopus.com/inward/citedby.url?scp=105016768577&partnerID=8YFLogxK
U2 - 10.1073/pnas.2416193122
DO - 10.1073/pnas.2416193122
M3 - Article
C2 - 40982673
AN - SCOPUS:105016768577
SN - 0027-8424
VL - 122
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 39
M1 - e2416193122
ER -