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The Fe snow regime in Ganymede's core: A deep-seated dynamo below a stable snow zone

Rückriemen, Tina and Breuer, D. and Spohn, T. (2015) The Fe snow regime in Ganymede's core: A deep-seated dynamo below a stable snow zone. Journal of Geophysical Research, 120 (6), pp. 1095-1118. Wiley. doi: 10.1002/2014JE004781. ISSN 0148-0227.

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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/2014JE004781/full


Ganymede shows signs of a present-day magnetic field, whose origin is thought to be in its core. The Fe snow regime has been suggested to be vital in Ganymede's history. In this regime, Fe crystals first form at the core-mantle boundary and later settle to the deeper core due to their higher density (Fe snow). A stable chemical gradient arises within the liquid of the snow zone. Below the snow zone the Fe particles remelt. We propose that the remelting of Fe in the deeper, entirely liquid core initiates compositional convection, which could be the origin of the dynamo. Such a dynamo is restricted by the period of time the snow zone needs to grow across the core. We investigate this time period with a 1-D core evolution model by varying the initial sulfur concentration, the core heat flux, and the thermal conductivity of the core. For the proposed dynamo in the deeper liquid core, we obtain necessary time periods of between 320 and 800 Myr and magnetic field strengths at the surface that match the observed value of 719 nT. To explain the present magnetic field, we favor cores with high sulfur concentrations because those lead to a late start and a long duration of the dynamo. Furthermore, a present dynamo below the snow zone suggests the absence of an inner core.

Item URL in elib:https://elib.dlr.de/101736/
Document Type:Article
Title:The Fe snow regime in Ganymede's core: A deep-seated dynamo below a stable snow zone
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Rückriemen, Tinatina.rueckriemen (at) dlr.deUNSPECIFIED
Breuer, D.doris.breuer (at) dlr.deUNSPECIFIED
Spohn, T.tilman.spohn (at) dlr.deUNSPECIFIED
Date:8 June 2015
Journal or Publication Title:Journal of Geophysical Research
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1002/2014JE004781
Page Range:pp. 1095-1118
EditorsEmailEditor's ORCID iD
Hauck, S. A.Department of Earth, Environmental, and Planetary Sciences Case Western Reserve University 10900 Euclid Avenue Cleveland, OH 44106-7216UNSPECIFIED
Baratoux, D.Université de Toulouse III - Observatoire Midi-Pyrénées Geosciences Environnement Toulouse 14, Avenue Edouard Belin 31400 ToulouseUNSPECIFIED
Stanley, S.University of Toronto Department of Physics Toronto, ON M5S1A7 CanadaUNSPECIFIED
Keywords:Fe snow, core evolution, magnetic field, Ganymede
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Space Exploration
DLR - Research theme (Project):R - Exploration of the Solar System
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research
Institute of Planetary Research > Planetary Physics
Institute of Planetary Research > Leitungsbereich PF
Deposited By: Rückriemen, Tina
Deposited On:07 Jan 2016 09:46
Last Modified:01 Dec 2018 19:51

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