Magma Ocean Evolution at Arbitrary Redox State

Area of Science:

• Planetary Science
• Geochemistry
• Atmospheric Science

Background:

• Magma ocean-atmosphere interactions drive outgassing, greenhouse forcing, and mantle melting on young rocky planets.
• Prior research focused on Earth-like planets, but exoplanet diversity necessitates exploring varied geochemical scenarios.

Purpose of the Study:

• Investigate how varying redox properties impact magma ocean solidification duration, thermodynamic state, mantle melt fraction, and atmospheric composition.
• Explore diverse geochemical scenarios for low-mass exoplanets with varying densities and irradiation.

Main Methods:

• Developed a 1D coupled interior-atmosphere model to simulate lava planet evolution.
• Applied the model to scenarios with varied redox states, orbital separations, hydrogen endowments, and C/H ratios around a Sun-like star.

Main Results:

• Planetary evolution paths range from permanent magma oceans to solidification within 1 Myr for an Earth-like planet at 1 AU.
• Solidified planets typically develop carbon monoxide (CO) or hydrogen (H2)-dominated atmospheres without atmospheric escape.
• Orbital separation is the dominant factor in magma ocean evolution, followed by hydrogen endowment, mantle oxygen fugacity, and C/H ratio.

Conclusions:

• Collisional absorption by CO can induce greenhouse effects, stalling or preventing magma ocean solidification.
• Geochemical properties significantly control the fate of magma oceans through greenhouse effects and volatile outgassing.