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Photon harvesting and rocky planet biosignatures with 3D climate models.

Presentation #410.08 in the session Exoplanet Atmospheres: Terrestrial Planets (Oral Presentation)

Published onOct 23, 2023
Photon harvesting and rocky planet biosignatures with 3D climate models.

On the Earth, phototrophic life uses the bulk of available energy, in the form of stellar photons. The most impactful phototrophic life on the Earth is also autotrophic, fixing carbon from the atmosphere and generating waste molecular oxygen. Consequently, the Earth’s environment has, via oxygenation, been radically altered starting some 2.45 Gyr ago, and undergoes dramatic seasonal variation as phototrophic life reacts to varying solar irradiance and environmental change. But what will photon harvesting and its consequences look like across the population of rocky exoplanets? We are applying a state-of-the-art 3D climate model (ROCKE-3D) to evaluate the detailed multi-wavelength stellar irradiance, temperature, and humidity at rocky planet surfaces (including cloud shadowing and atmospheric re-radiation). Photon harvesting characteristics can then be mapped across a range of exoplanet scenarios with varying planet spin, orbit, land-ocean configurations, host stellar type, and even topography. These data are then used to estimate photosynthetic productivity to look for correlations between planetary properties and biomarkers such as atmospheric oxygen and active carbon cycling. Striking, and complex differences are seen between planets with fast and slow rotation periods (daylengths). A goal of this research is to determine the consequences for future searches for biosignatures with instruments such as JWST, ELTs and the Habitable Worlds Observatory.

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