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. 2018 Feb 1;18(2):133–189. doi: 10.1089/ast.2016.1589

FIG. 15.

FIG. 15.

Similar to the reflected light spectra of Fig. 12, but for the 1 bar desiccated CO2/O2/CO atmosphere with a wavelength-dependent Mars average surface albedo (top panel), preindustrial Earth (middle panel), and Archean Earth (bottom panel). The top panel shows a desiccated planet with an outgassed CO2 atmosphere, which can support a stable CO2/O2/CO/O3 atmosphere without life (Gao et al., 2015). The lack of H2O is an indicator of the abiotic nature of the atmospheric O2. The middle panel shows Proxima Centauri b simulated as an Earth-like planet with 21% O2 and 5% CO2, and 50% cloud cover. The UV to NIR spectrum contains features from Rayleigh scattering, O3, O2, H2O, CO2, and CH4. The bottom panel shows Archean Earth-like planets with a photochemically self-consistent organic haze (orange) and without a haze (purple). Note the overlap of some H2O and CH4 absorption bands and the strong haze absorption feature at short wavelengths. The surface albedo assumes the composite albedo described in Section 3.7.5 with no vegetation.