In:
Nature, Springer Science and Business Media LLC, Vol. 617, No. 7961 ( 2023-05-18), p. 483-487
Abstract:
Photochemistry is a fundamental process of planetary atmospheres that regulates the atmospheric composition and stability 1 . However, no unambiguous photochemical products have been detected in exoplanet atmospheres so far. Recent observations from the JWST Transiting Exoplanet Community Early Release Science Program 2,3 found a spectral absorption feature at 4.05 μm arising from sulfur dioxide (SO 2 ) in the atmosphere of WASP-39b. WASP-39b is a 1.27-Jupiter-radii, Saturn-mass (0.28 M J ) 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 SO 2 in such an atmosphere is through photochemical processes 5,6 . Here we show that the SO 2 distribution computed by a suite of photochemical models robustly explains the 4.05-μm spectral feature identified by JWST transmission observations 7 with NIRSpec PRISM (2.7 σ ) 8 and G395H (4.5 σ ) 9 . SO 2 is produced by successive oxidation of sulfur radicals freed when hydrogen sulfide (H 2 S) is destroyed. The sensitivity of the SO 2 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 SO 2 also shows observable features at ultraviolet and thermal infrared wavelengths not available from the existing observations.
Type of Medium:
Online Resource
ISSN:
0028-0836
,
1476-4687
DOI:
10.1038/s41586-023-05902-2
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2023
detail.hit.zdb_id:
120714-3
detail.hit.zdb_id:
1413423-8
SSG:
11
