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Flux ropes in the Hermean magnetotail: distribution, properties and formation

Smith, A.W., Slavin, J.A., Jackman, C.M., Poh, G.-K. and Fear, R.C. (2017) Flux ropes in the Hermean magnetotail: distribution, properties and formation Journal of Geophysical Research: Space Physics (doi:10.1002/2017JA024295).

Record type: Article


An automated method was applied to identify magnetotail flux rope encounters in MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) magnetometer data. The method identified significant deflections of the north-south component of the magnetic field coincident with enhancements in the total field or dawn-dusk component. Two hundred forty-eight flux ropes are identified that possess well-defined minimum variance analysis (MVA) coordinate systems, with clear rotations of the field. Approximately 30% can be well approximated by the cylindrically symmetric, linearly force-free model. Flux ropes are most common moving planetward, in the postmidnight sector. Observations are intermittent, with the majority (61%) of plasma sheet passages yielding no flux ropes; however, the peak rate of flux ropes during a reconnection episode is ∼5 min−1. Overall, the peak postmidnight rate is ∼0.25 min−1. Only 25% of flux ropes are observed in isolation. The radius of flux ropes is comparable to the ion inertial length within Mercury's magnetotail plasma sheet. No clear statistical separation is observed between tailward and planetward moving flux ropes, suggesting the near-Mercury neutral line (NMNL) is highly variable. Flux ropes are more likely to be observed if the preceding lobe field is enhanced over background levels. A very weak correlation is observed between the flux rope core field and the preceding lobe field orientation; a stronger relationship is found with the orientation of the field within the plasma sheet. The core field strength measured is ∼6 times stronger than the local dawn-dusk plasma sheet magnetic field.

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Accepted/In Press date: 17 July 2017
e-pub ahead of print date: 3 August 2017


Local EPrints ID: 412941
ISSN: 2169-9380
PURE UUID: e358675f-38b6-40d2-86df-3b2a2f27b8de
ORCID for A.W. Smith: ORCID iD
ORCID for R.C. Fear: ORCID iD

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Date deposited: 09 Aug 2017 16:31
Last modified: 09 Aug 2017 16:31

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Author: A.W. Smith ORCID iD
Author: J.A. Slavin
Author: C.M. Jackman
Author: G.-K. Poh
Author: R.C. Fear ORCID iD

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