Modelling of homogeneous accretion & multi-stage core formation (all models considering the delivery of water and carbon from the beginning of Earth accretion). Similar to Fig. 6a except that calculated core concentrations of H and C (black dotted and broken lines, respectively) and those required to explain the outer core density deficit when TICB = 6000 K (red curve), 5400 K (green) and 4800 K (right blue) are given in the right panel for each model. H2O and C concentrations in each non-carbonaceous (red) and carbonaceous chondrite (blue) are also shown. See text for more details. — astro-ph.EP
We determined the metal/silicate partition coefficients of hydrogen and carbon, DH and DC, simultaneously under typical conditions of Earth’s core formation.
Experiments demonstrate that both DH and DC diminish in the presence of carbon and hydrogen, respectively, indicating their strong interactions in liquid metal. With these partitioning data, we investigated the core and bulk Earth abundances of hydrogen and carbon based on core formation scenarios that are compatible with the bulk silicate Earth composition and the mass fraction and density deficit of the core.
The results of the single-stage core formation modelling are markedly different from those using DH and DC individually determined in earlier experiments, indicating that the Earth building blocks do not match enstatite chondrites in water abundance and require contributions by carbonaceous chondrites.
The multi-stage core formation models combined with an Earth accretion scenario accounting for isotopic composition show 0.18-0.49 wt% H and 0.19-1.37 wt% C in the core, leading to 0.53-1.40 wt% H2O (present as H in the core) and 0.07-0.44 wt% C in the bulk Earth. Our modelling also demonstrates that up to 53% and 72% of Earth’s water (hydrogen) and carbon, respectively, could have been derived from non-carbonaceous chondritic materials.
Yutaro Tsutsumi (1), Naoya Sakamoto (2), Kei Hirose (1 and 3), Shuhei Mita (1), Shunpei Yokoo (1), Han Hsu (4), Hisayoshi Yurimoto (2 and 5) ((1) Department of Earth and Planetary Science, The University of Tokyo, Bunkyo, Tokyo, Japan (2) Institute for Integrated Innovations, Hokkaido University, Sapporo, Hokkaido, Japan (3) Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo, Japan (4) Department of Physics, National Central University, Taoyuan City, Taiwan (5) Department of Natural History Sciences, Hokkaido University, Sapporo, Hokkaido, Japan)
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Materials Science (cond-mat.mtrl-sci)
Cite as: arXiv:2508.17740 [astro-ph.EP] (or arXiv:2508.17740v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2508.17740
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From: Kei Hirose
[v1] Mon, 25 Aug 2025 07:32:18 UTC (6,162 KB)
https://arxiv.org/abs/2508.17740
Astrobiology,