Image Details
Caption: Figure 7.
Comparison between the atmosphere + SC abundance posteriors and VULCAN chemical equilibrium predictions for CO2 and CO. The blue histograms show the full-spectrum atmosphere + SC posterior distributions, while the orange histograms show the truncated atmosphere + SC posterior distributions (excluding data beyond 4.7 μm). The black solid and dashed vertical lines mark the posterior median and 1σ bounds, respectively. Colored curves show VULCAN equilibrium abundance profiles for 1×, 10×, and 100 × solar metallicity, with solid lines indicating solar C/O (0.55) and dashed lines indicating supersolar C/O (1). Lower-metallicity models fall below the plotted abundance range. The pressure axis is restricted to the approximate region probed, estimated from pressure contribution functions. The full-spectrum atmosphere + SC retrieval yields CO2 and CO abundances above the low-metallicity equilibrium expectations, suggesting disequilibrium chemistry would be required. In contrast, the truncated atmosphere + SC retrieval yields lower abundances more consistent with equilibrium predictions, highlighting that conclusions about chemical disequilibrium are sensitive to the wavelength range included in the retrieval.
© 2026. The Author(s). Published by the American Astronomical Society.