Proxima Centauri b: Multistate Climate-Photochemical Futures and Their Observational Signatures

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A study using self-consistent 1-D climate–photochemical models and radiative transfer shows Proxima Centauri b could have a range of climates from uninhabitable to habitable, including abiotic oxygen-rich or CO2-dominated desiccated atmospheres and Earth-like states with or without oceans, shaped by the star’s history and orbital dynamics and by atmospheric replenishment, with observables like phase curves, transmission and direct-imaging spectra used to distinguish these states and identify signs such as O4 from massive O2, CO/CO2 bands, water vapor, methane, and haze, while noting that ocean glint and future telescope capabilities (JWST, large space or ground-based ELTs) will influence the detectability of surface water and key gases; the conclusion is that Proxima Cen b could span climates from uninhabitable to potentially habitable depending on volatiles, atmospheric evolution, and rotation, and several researchers including Victoria S. Meadows, Giada N. Arney, Edward W. Schwieterman, Jacob Lustig-Yaeger, Andrew P. Lincowski, and Tyler Robinson contribute to this interdisciplinary forecast.