Extended Data Fig. 8: Grid of self-consistent models for various volatile (C–H–O–N–S–P) compositions.

a, Emission spectra and temperature profiles of best-fit volatile-only models compared with variant models enriched by rock-forming elements. The labels denote the dominant atmospheric constituents, as well as the C/O ratio and heat redistribution parameter. χ² values represent the minimum achieved when allowing the NIRCam mean eclipse depth to vary freely, and the NIRCam data are shown with a mean eclipse depth of 55 ppm. The two magenta data points represent previous Spitzer observations²⁴. b, χ² values against the C + O mole fraction and the initial C/O ratio for three NIRCam mean eclipse depths for f = 2/3 grid models. c, Same as panel b but for models with f = 0.3. d, Minimum achieved χ² values when the NIRCam mean depth is allowed to vary freely. The leftmost panel includes both NIRCam and MIRI data; the middle panel shows the minimum χ² values when only fitting the NIRCam data; the rightmost panel shows the minimum χ² values when only fitting the MIRI data.