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Numerical simulations on origin of Galilean moons’ magnetic anomalies

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Abstract

Galileo mission detected the magnetic anomalies originated from Galilean moons. These anomalies are likely generated in the moons’ interiors, under the influence of a strong ambient Jovian field. Among various possible generation mechanisms of the anomalies, we focus on magneto-convection and dynamos in the interiors via numerical simulation. To mimic the electromagnetic environment of the moons, we introduce in our numerical model an external uniform magnetic field B 0 with a fixed orientation but varying field strength. Our results show that a finite B 0 can substantially alter the dynamo processes inside the core. When the ambient field strength B 0 increases to approximately 40% of the field generated by the pure dynamo action, the convective state in the core changes significantly: the convective flow decreases by 80% in magnitude, but the differential rotation becomes stronger in much of the fluid layer, leading to a stronger field generated in the core. The field morphologies inside the core tend to align with the ambient field, while the flow patterns show the symmetry-breaking effect under the influence of B 0. Furthermore, the generated field tends to be temporally more stable.

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Authors and Affiliations

  1. Laboratory of Computational Geodynamics, College of Earth Sciences, Graduate University of Chinese Academy of Sciences, Beijing, 100049, China

    LiGuo Jiao & ShiZhuang Ma

  2. NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA

    WeiJia Kuang

Authors
  1. LiGuo Jiao
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  2. WeiJia Kuang
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  3. ShiZhuang Ma
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Correspondence to LiGuo Jiao.

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Jiao, L., Kuang, W. & Ma, S. Numerical simulations on origin of Galilean moons’ magnetic anomalies. Sci. China Earth Sci. 54, 1754–1760 (2011). https://doi.org/10.1007/s11430-011-4276-0

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  • DOI: https://doi.org/10.1007/s11430-011-4276-0

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