Extrasolar Planets

Hidden Water In Magma Ocean Exoplanets

By Keith Cowing
October 28, 2021
Filed under
Hidden Water In Magma Ocean Exoplanets
Three model scenarios employed in our study. Model (A) is very similar to models presented in Dorn et al. (2015) and Dorn et al. (2017b) and other commonly used exoplanet interior models follow model (A), where liquid rock phases are neglected. Characteristically, the total radius is largest for model (B), where solid and melt phases are present in the core and the mantle. Generally, the radius is smallest for model (C), where additionally the effect of water partitioning into the magma ocean is taken into account. Model C most accurately reflects our current knowledge of mineral physics and exoplanet interiors.

We demonstrate that the deep volatile storage capacity of magma oceans has significant implications for the bulk composition, interior and climate state inferred from exoplanet mass and radius data.

Experimental petrology provides the fundamental properties on the ability of water and melt to mix. So far, these data have been largely neglected for exoplanet mass-radius modeling. Here, we present an advanced interior model for water-rich rocky exoplanets.

The new model allows us to test the effects of rock melting and the redistribution of water between magma ocean and atmosphere on calculated planet radii. Models with and without rock melting and water partitioning lead to deviations in planet radius of up to 16% for a fixed bulk composition and planet mass.

This is within current accuracy limits for individual systems and statistically testable on a population level. Unrecognized mantle melting and volatile redistribution in retrievals may thus underestimate the inferred planetary bulk water content by up to one order of magnitude.

Caroline Dorn, Tim Lichtenberg

Comments: 13 pages, 5 figures, ApJL, video summary can be found here: this https URL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2110.15069 [astro-ph.EP] (or arXiv:2110.15069v1 [astro-ph.EP] for this version)
Submission history
From: Caroline Dorn
[v1] Thu, 28 Oct 2021 12:41:25 UTC (2,252 KB)

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