Water/Hycean Worlds & Oceanography

Was Earth’s Water Acquired Locally During The Earliest Phases Of The Solar System Formation?

By Keith Cowing

Status Report

astro-ph.EP

July 8, 2025

Filed under astro-ph.EP, astrochemistry, astrogeology, Earth, habitability, interstellar icy grains, Proto-Solar Nebula, Protoplanetary Disk, Water, water snowline

Was Earth’s Water Acquired Locally During The Earliest Phases Of The Solar System Formation? — Water-equivalent content by weight in the Solar System and model predictions. Left upper panel: Midplane temperature of the disk using T_1au = 145, 180, 200 and 300 K (from light blue to dark blue respectively) in Eq. 2. Left lower panel: The solid curves show the snowlines calculated using the Tinacci et al. (2023) BE distribution for the different temperature profiles (colours code as above). The data points show the median values of the water-equivalent content by weight for different objects of the Solar System (Sec. 3), where vertical bars represent the minimum and maximum range. Please note that the values reported in Tab. 1 are considered upper limits (see text). The uncertainty of the formation region of the various objects are shown as ellipses, distinguishing NC, CC, and comet populations. Right: Computed snowlines using T_1au = 200 K in Eq. 2 and different models (see text): BE distribution (solid line), single BE (dashed) and condensation at 180 K (dotted). The right and left panels share the same vertical axis. — astro-ph.EP

The origin of the terrestrial water remains debated, as standard Solar System formation models suggest that Earth formed from dry grains, inside the snowline of the Proto-Solar Nebula (PSN).

Here, we revisit this issue through the lens of computational chemistry. While the classically used snowline relies on a single condensation temperature, recent work in quantum chemistry shows that the binding energy of water on icy grains has a gaussian distribution, which implies a gradual sublimation of water rather than a sharp transition. We use the computed distribution of binding energies to estimate the radial distribution of adsorbed ice on the dust grains across the PSN protoplanetary disk.

Our model reproduces the full range of estimated water abundances on Earth and matches the hydration trends observed in chondrite groups at their predicted formation distances. Thus, we suggest that a significant fraction of Earth’s water may have been acquired locally at early stages of the Solar System formation, without requiring delivery from beyond the classical snowline.

Lise Boitard-Crépeau, Cecilia Ceccarelli, Pierre Beck, Lionel Vacher, Piero Ugliengo

Comments: 7 pages, 2 figures, published in ApJL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2507.03968 [astro-ph.EP] (or arXiv:2507.03968v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2507.03968
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Journal reference: ApJL 987 (2025) L25
Related DOI:
https://doi.org/10.3847/2041-8213/ade5aa
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Submission history
From: Lise Boitard-Crépeau
[v1] Sat, 5 Jul 2025 09:17:34 UTC (740 KB)
https://arxiv.org/abs/2507.03968
Astrobiology,

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) 🖖🏻

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