Revealing the Core Dynamics of Vesta: Insights from Experimental Investigations of Electrical Resistivity and Thermal Conductivity
Abstract
Insights from high pressure and temperature experiments involving in-situ measurements of the electrical resistivity of Fe-5wt%Ni at temperatures of up to 2000 K, under pressures of 2-5 GPa in a 1000-ton cubic-anvil press have been used to reveal Vesta’s core dynamics. The Wiedemann–Franz law was used to calculate the thermal conductivity from the measured electrical resistivity data. Comparing the findings of this study with prior investigations on both pure Fe and Fe-10wt%Ni indicates that an increase in Ni ranging from 0-10wt% has negligible effect on the electrical resistivity of Fe alloys. By comparing the range of estimated heat flux through the core-mantle boundary of 1.5–78 GW to the estimated adiabatic core heat flux ~331 MW at the top of Vesta’s core determined in this study, we conclude that the mechanism behind Vesta’s past core dynamo that generated its surface magnetic field during its early history was thermal convection.