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Electrical conductivity and magnetic dynamos in magma oceans of Super-Earths.

ABSTRACT: Super-Earths are extremely common among the numerous exoplanets that have been discovered. The high pressures and temperatures in their interiors are likely to lead to long-lived magma oceans. If their electrical conductivity is sufficiently high, the mantles of Super-Earth would generate their own magnetic fields. With ab initio simulations, we show that upon melting, the behavior of typical mantle silicates changes from semi-conducting to semi-metallic. The electrical conductivity increases and the optical properties are substantially modified. Melting could thus be detected with high-precision reflectivity measurements during the short time scales of shock experiments. We estimate the electrical conductivity of mantle silicates to be of the order of 100??-1?cm-1, which implies that a magnetic dynamo process would develop in the magma oceans of Super-Earths if their convective velocities have typical values of 1?mm/s or higher. We predict exoplanets with rotation periods longer than 2 days to have multipolar magnetic fields.

SUBMITTER: Soubiran F

PROVIDER: S-EPMC6155165 | biostudies-other | 2018 Sep

REPOSITORIES: biostudies-other

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Electrical conductivity and magnetic dynamos in magma oceans of Super-Earths.

Soubiran François F Militzer Burkhard B

Nature communications 20180924 1

Super-Earths are extremely common among the numerous exoplanets that have been discovered. The high pressures and temperatures in their interiors are likely to lead to long-lived magma oceans. If their electrical conductivity is sufficiently high, the mantles of Super-Earth would generate their own magnetic fields. With ab initio simulations, we show that upon melting, the behavior of typical mantle silicates changes from semi-conducting to semi-metallic. The electrical conductivity increases an ...[more]

PMID: 30250296

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