Signatures of Magnetic Separatrices at the Borders of a Crater Flux Transfer Event Connected to an Active X‐Line

Trenchi, L., Coxon, John, Fear, R. C., Eastwood, J. P., Dunlop, M. W., Trattner, K. J., Gershman, D. J., Graham, D. B., Khotyaintsev, Yu. and Lavraud, B. (2019) Signatures of Magnetic Separatrices at the Borders of a Crater Flux Transfer Event Connected to an Active X‐Line. Journal of Geophysical Research: Space Physics, 124 (11). pp. 8600-8616. ISSN 2169-9380

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Official URL: https://doi.org/10.1029/2018JA026126

Abstract

In this paper, we present Magnetospheric Multiscale (MMS) observations of a flux transfer event (FTE) characterized by a clear signature in the magnetic field magnitude, which shows maximum at the center flanked by two depressions, detected during a period of stable southward interplanetary magnetic field. This class of FTEs are called “crater-FTEs” and have been suggested to be connected with active reconnection X line. The MMS burst mode data allow the identification of intense fluctuations in the components of the electric field and electron velocity parallel to the magnetic field at the borders of the FTE, which are interpreted as signatures of the magnetic separatrices. In particular, the strong and persistent fluctuations of the parallel electron velocity at the borders of this crater-FTE reported for the first time in this paper, sustain the field-aligned current part of the Hall current system along the separatrix layer, and confirm that this FTE is connected with an active reconnection X line. Our observations suggest a stratification of particles inside the reconnection layer, where electrons are flowing toward the X line along the separatrix, are flowing away from the X line along the reconnected field lines adjacent to the separatrices, and more internally ions and electrons are flowing away from the X line with comparable velocities, forming the reconnection jets. This stratification of the reconnection layer forming the FTE, together with the reconnection jet at the trailing edge of the FTE, suggests clearly that this FTE is formed by the single X line generation mechanism.

Item Type: Article
Additional Information: Funding Information: Work at Southampton was supported by the UK Science and Technology Facilities Council (STFC) Ernest Rutherford Grant ST/L002809/1, and R. C. F. was supported by Ernest Rutherford Fellowship ST/K004298/2.
Subjects: F300 Physics
F500 Astronomy
F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Rachel Branson
Date Deposited: 22 Feb 2022 12:11
Last Modified: 22 Feb 2022 12:15
URI: http://nrl.northumbria.ac.uk/id/eprint/48515

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