[A-OS25] Continental-Oceanic Mutual Interaction: Planetary scale Material Circulation

[AOS25-01] Impact of Extreme UV fluxes on Atmospheric Escape of the Hadean Earth and Earth-like Exoplanets

★Invited Papers

*Vladimir Airapetian^1,2, Jared Bell¹, Alex Glocer¹ (1.NASA Goddard Space Flight Center, 2.American University, DC)

Keywords:Hadean Earth, exoplanets, atmospheric escape

Upper atmospheres of the Hadean Earth and Earth-like exoplanets were (are) exposed to large fluxes of X-ray and Extreme UV radiations. To understand the impact of XUV fluxes on atmospheric erosion, we adapted the Earth Global Ionosphere-Thermosphere Hydrodynamic Model (GITM). In particular, we examined the response of the upper atmospheres when the solar/stellar flux is increased up to 100 times of the current solar XUV flux. We find that while the early (Hadean) Earth’s atmospheric erosion is driven by ion (O⁺ and N⁺) escape via polarization electric field, atmospheres of Earth-like exoplanets located in habitable zones around active K and M dwarfs should undergo massive hydrodynamic escape. We model the atmospheric expansion of both N₂-dominated atmospheres and quantify the effect of its potential enhancement to the rate of atmospheric escape. We also derive the response of the key cooling mechanisms: CO₂ and NO at an Earth-like exoplanet and discuss their observational signatures in the mid-IR band.