The Role Of Interior Dynamics and Differentiation on the Surface and Atmosphere of Lava Planets

Lava planets are rocky exoplanets that orbit so close to their host star that their day-side is hot enough to melt silicate rock. Their short orbital periods ensure that lava planets are tidally locked into synchronous rotation, with permanent day and night hemispheres. Such asymmetric magma oceans have no analogs in the Solar System and will exhibit novel fluid dynamics.

Here we report numerical simulations of lava planet interiors showing that solid-liquid fractionation in the planetary interior has a major impact on the compositional structure and evolution of the planet. We explored two styles of dynamics that depend primarily on the interior thermal state : 1) a hot fully molten interior, and 2) a mostly solid interior with a shallow day-side magma ocean.

In the hot interior scenario, the atmosphere reflects the planet’s bulk silicate composition and the night-side crust is gravitationally unstable and constantly replenished. In the cool interior scenario, the distilled atmosphere will lack Na, K and FeO, and the night-side mantle is entirely solid, with a cold surface. These two end-member cases can be distinguished with observations from the James Webb Space Telescope, offering an avenue to probe the diversity of terrestrial exoplanet evolutions.

3D simulations of global magma ocean dynamics accounting for rotation. Left panels show snapshots, while the right panels show time averages over 14 turbulent turnover times. The top panels show equatorial slices, while the bottom panels show meridional slices. In these simulations with a fully molten, turbulent magma ocean, rotation produces a longitudinal shift of downwelling and upwelling regions with respect to the antistellar and sub-stellar points, visible in panel (b). An asymmetry between the western and eastern hemispheres also develops in the bulk of the magma ocean. — astro-ph.EP

Charles-Édouard Boukaré, Daphné Lemasquerier, Nicolas Cowan, Henri Samuel, James Badro

Comments: 12 pages, 4 figures. Supplementary informations are included
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Fluid Dynamics (physics.flu-dyn); Geophysics (physics.geo-ph)
Cite as: arXiv:2308.13614 [astro-ph.EP] (or arXiv:2308.13614v2 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2308.13614
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Submission history
From: Charles-Édouard Boukaré
[v1] Fri, 25 Aug 2023 18:15:14 UTC (11,138 KB)
[v2] Tue, 20 May 2025 14:45:33 UTC (13,401 KB)
https://arxiv.org/abs/2308.13614
Astrobiology, Astrogeology,