Transmission and emission spectra for stable atmospheres for T-1 b. The transmission and emission columns and atmosphere archetypes (rows) are the same as for Figure 6, except that T-1 b had no stable, realistic atmospheres of the H₂O-dominated or H₂O–CO₂ outgassed, O₂-dominated archetypes, so those rows are not presented. The only atmospheres that fit the T-1 b emission data (T. P. Greene et al. 2023; M. Gillon et al. 2026; E. Ducrot et al. 2025) to the ∼2σ level are H₂O outgassed, O₂-dominated atmospheres with pressures of ∼0.005 bar. The T-1 b mixed CO₂–CO and mixed O₂–H₂O–CO₂ spectra shown in black indicate that they are confidently ruled out by the emission data (fitting at a χ² of ∼100).