Venus-analog Archives

Schematic overview of coupled redox-atmosphere-interior evolution model, PACMAN-P. The model is initialized with a completely molten mantle, and the solidification radius, rs, evolves from the core-mantle boundary to the surface, rp, as the planet cools. At each timestep, we calculate multiphase thermochemical equilibrium between C, H, O, and Fe-bearing species to find the mantle redox state and the partitioning of volatiles between the magma ocean and the atmosphere. Surface climate, Tsurf, is calculated using a radiative-convective model given atmospheric volatile inventories. Under highly reducing conditions created by large H2 envelopes, the reaction of H2 with the silicate magma ocean produces metallic iron, that is either sequestered in the core or remains in the mantle (two endmember assumptions). Atmospheric escape is either XUV-limited or diffusion limited depending on stratospheric composition, and under the former regime we calculate the hydrodynamic drag of O and CO. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report, TRAPPIST-1

The Erosion Of Large Primary Atmospheres Typically Leaves Behind Substantial Secondary Atmospheres On Temperate Rocky Planets

by Keith CowingOctober 1, 2024October 1, 2024

Exoplanet exploration has revealed that many–perhaps most–terrestrial exoplanets formed with substantial H2-rich envelopes, seemingly in contrast to solar system terrestrials, for which there is scant evidence of long-lived primary atmospheres. […]