FIG. 11.

Synthetic thermal phase curve variation spectrum of the photochemically self-consistent Earth-like atmospheric case with 50% cloud coverage (top panel), the hazy Archean-like atmospheric case with 50% cloud coverage (second panel), the desiccated O₂-rich atmospheric case (third panel), and the 90 bar cloudy Venus-like atmospheric case (bottom panel). The solid and gray lines show the emitted flux from the dayside of the planet (observed at 0°) minus the emitted flux from the nightside of the planet (observed at 180°), divided by the average flux received from the star plus planet. The solid line depicts the maximum possible signal strength for a phase curve spectrum of the planet in the case that there is no flux emitted from the nightside, while the gray line shows the signal strength for a case with a nightside 20 K cooler than the dayside. The colored horizontal lines show the high-resolution model spectrum convolved with the 7 JWST/MIRI filter bands longward of where Proxima Centauri exceeds the instrument brightness limit. Each upper-left inset shows the phase-dependent planet-to-star flux contrast ratios in the MIRI filter bands for the cases with no flux from the nightside (solid lines) and with a 20 K cooler nightside (dotted lines).