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Title: 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 Ω -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.

Authors:
ORCiD logo [1];  [2]
  1. Univ. of California, Berkeley, CA (United States); Univ. Lyon (France)
  2. Univ. of California, Berkeley, CA (United States)
Publication Date:
Research Org.:
Univ. of California, Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1511436
Grant/Contract Number:  
SC0016248
Resource Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 9; Journal Issue: 1; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES

Citation Formats

Soubiran, François, and Militzer, Burkhard. Electrical conductivity and magnetic dynamos in magma oceans of Super-Earths. United States: N. p., 2018. Web. doi:10.1038/s41467-018-06432-6.
Soubiran, François, & Militzer, Burkhard. Electrical conductivity and magnetic dynamos in magma oceans of Super-Earths. United States. doi:10.1038/s41467-018-06432-6.
Soubiran, François, and Militzer, Burkhard. Mon . "Electrical conductivity and magnetic dynamos in magma oceans of Super-Earths". United States. doi:10.1038/s41467-018-06432-6. https://www.osti.gov/servlets/purl/1511436.
@article{osti_1511436,
title = {Electrical conductivity and magnetic dynamos in magma oceans of Super-Earths},
author = {Soubiran, François and Militzer, Burkhard},
abstractNote = {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 Ω-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.},
doi = {10.1038/s41467-018-06432-6},
journal = {Nature Communications},
number = 1,
volume = 9,
place = {United States},
year = {2018},
month = {9}
}

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