Extended Data Fig. 9: The CO2/H2O ratio versus metallicity.
From: Hydrogen sulfide and metal-enriched atmosphere for a Jupiter-mass exoplanet
Transmission spectroscopy is directly shaped by the relative elemental abundance within the atmosphere from ~ 1 to 0.001 mbar. Although free retrieval results can have degeneracies between different molecular abundances, they are robust at reflecting their relative ratios. The CO2/H2O from the free retrieval (brown) is consistent to within 1 sigma (shaded region) of CO2/H2O value at ~ 3 time solar metallicity from the grid models. As we do not expect CO2 or H2O abundance to vary significantly from the equilibrium chemistry predictions for this planet, this agreement shows that free retrieval is consistent with the super-stellar metallicity inferred by the grid retrieval.
