Lava / Volcanic Worlds

Chemical Evolution Of An Evaporating Lava Pool

By Keith Cowing

Status Report

astro-ph.EP

November 24, 2024

Filed under astrgeology, astro-ph.EP, astrochemistry, atmosphere, emission spectroscopy, exoplanet, lava, lava pool, lava world, Magma, Mantle, silicate atmosphere, volcanology

Chemical Evolution Of An Evaporating Lava Pool — [L] The amount of mass removed from planets with different initial masses and substellar temperatures at different ages (the top panel corresponds to 1 Gyr and the bottom to 10 Gyrs). Planets lose mass according to the models of Booth et al. (2023). Colours plot mass lost / initial planet mass while white contours plot log10( mass lost / pool mass) at the specified age. See the text for a discussion of the pool mass. Red circles show the estimated current mass of planets in the exoplanet archive. (These are generally large planets, that will not change significantly in mass over their lifetimes). The box-like shape of the colour contours in the top left is an artefact of the finite grid of temperatures that the mass loss models were run for. — astro-ph.EP [R] The amount of mass removed from lava pools via day-tonightside winds for planets of different initial masses and substellar temperatures and at different ages. The composition of the material removed in the day-to-nightside wind is assumed to be SiO. The planets’ total masses also decrease due to mass loss according to the models of Booth et al. (2023). The colours show the amount of mass removed / the initial mass of the planet, while the white contours show log10( amount of mass removed / pool mass ) at the specified age. See the text for a discussion of the pool mass. Red circles show planets in the exoplanet archive. — astro-ph.EP

Many known rocky exoplanets are so highly irradiated that their dayside surfaces are molten, and `silicate atmospheres’, composed of rock-forming elements, are generated above these lava pools.

The compositions of these ‘lava planet’ atmospheres are of great interest because they must be linked to the composition of the underlying rocky interiors. It may be possible to investigate these atmospheres, either by detecting them directly via emission spectroscopy or by observing the dust tails which trail the low mass ‘catastrophically evaporating planets’.

In this work, we develop a simple chemical model of the lava pool–atmosphere system under mass loss, to study its evolution. Mass loss can occur both into space and from the day to the nightside.

We show that the system reaches a steady state, where the material in the escaping atmosphere has the same composition as that melted into the lava pool from the mantle. We show that the catastrophically evaporating planets are likely to be in this evolved state. This means that the composition of their dust tails is likely to be a direct trace of the composition of the mantle material that is melted into the lava pool.

We further show that, due to the strength of day-to-nightside atmospheric transport, this evolved state may even apply to relatively high-mass planets (>1 Earth Mass). Moreover, the low pressure of evolved atmospheres implies that non-detections may not be due to the total lack of an atmosphere. Both conclusions are important for the interpretation of future observations.

Alfred Curry, Subhanjoy Mohanty, James E. Owen

Comments: Accepted for publication in MNRAs. 19 pages, 15 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2411.13686 [astro-ph.EP] (or arXiv:2411.13686v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2411.13686
Focus to learn more
Related DOI:
https://doi.org/10.1093/mnras/stae2583
Focus to learn more
Submission history
From: Alfred Curry
[v1] Wed, 20 Nov 2024 20:05:26 UTC (865 KB)
https://arxiv.org/abs/2411.13686
Astrobiology, Astrogeology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

Follow on Twitter