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A laboratory model for iron snow in planetary cores
  • Ludovic Huguet,
  • Michael Le Bars,
  • Renaud Deguen
Ludovic Huguet
ISTerre, Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, IRD, Université Gustave Eiffel, 38000 Grenoble, France

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Michael Le Bars
CNRS, Aix Marseille Univ, Centrale Marseille, IRPHE
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Renaud Deguen
Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, Univ. Gustave Eiffel, ISTerre,
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Solidification of the cores of small planets and moons is thought to occur in the â\euro˜iron snowâ\euro™ regime, in which iron crystals form near the core-mantle boundary and fall until re-melting at higher depth. The resulting buoyancy flux may sustain convection and dynamo action. This regime is poorly known, having never been observed in the field or laboratory. Here we present the first laboratory experiments designed to model iron snow. We find that solidification happens in a cyclic pattern, with intense solidification bursts separated by crystal-free periods. This is explained by the necessity of reaching a finite amount of supercooling to re-initiate crystallization once the crystals formed earlier have migrated away. When transposed to planetary cores, our results suggest that crystallization and the associated buoyancy flux would be strongly heterogeneous in time and space, which eventually impacts the time variability and geometry of the magnetic field.
03 Sep 2023Submitted to ESS Open Archive
11 Sep 2023Published in ESS Open Archive