Fig. 3: Observed flux of TRAPPIST-1 c and various emission models.
From: No thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c
Simulated emission spectra compared with the measured eclipse depth of TRAPPIST-1 c (red diamond, with the vertical error bar representing the 1σ uncertainty on the measured eclipse depth). The CO2 feature overlaps directly with the MIRI F1500W filter used for these observations. The two limiting cases for the atmospheric circulation for a zero-albedo planet (zero heat redistribution, that is, instant reradiation of incoming flux and global heat redistribution) are marked with dashed lines. Two cloud-free, O2/CO2 mixture atmospheres are shown with purple and red solid lines. They show decreased emission at 15 µm owing to CO2 absorption. A bare-rock model assuming an unweathered ultramafic surface of the planet with a Bond albedo of 0.5 is shown by the solid black line (see text for more information on weathering, including a full comparison of our measurement to a suite of surfaces in Extended Data Fig. 5). The cloudy Venus forward model with a surface pressure of 10 bar is shown with a solid yellow line.
