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MESSENGER Observations of Extreme Loading and Unloading of Mercury’s Magnetic Tail

TLDR
Observations during MESSENGER's third flyby of Mercury suggest that magnetic open flux loads the magnetosphere, which is subsequently unloaded by substorms—magnetic disturbances during which energy is rapidly released in the magnetotail.
Abstract
During MESSENGER's third flyby of Mercury, a series of 2-3 minute long enhancements of the magnetic field in the planet's magnetotail were observed. Magnetospheric substorms at Earth are powered by similar tail loading, but the amplitude is approximately 10 times less and the durations are 1 hr. These observations of extreme loading imply that the relative intensity of substorms at Mercury must be much larger than at Earth. The correspondence between the duration of tail enhancements and the calculated approximately 2 min Dungey cycle, which describes plasma circulation through Mercury's magnetosphere, suggests that such circulation determines substorm timescale. A key aspect of tail unloading during terrestrial substorms is the acceleration of energetic charged particles. Such signatures are puzzlingly absent from the MESSENGER flyby measurements.

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Journal ArticleDOI

Low‐degree structure in Mercury's planetary magnetic field

TL;DR: The structure of the magnetic field of Mercury was determined from analysis of orbital magnetometer measurements by the MESSENGER spacecraft as mentioned in this paper, where the magnetic equator was identified on 531 low altitude and 120 high altitude equator crossings from the zero in the radial cylindrical magnetic field component.
References
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Journal ArticleDOI

Neutral line model of substorms: Past results and present view

TL;DR: In this article, the authors reviewed the NENL model of magnetospheric substorms, including the role of coupling with the solar wind and interplanetary magnetic field, the growth phase sequence, the expansion phase (and onset), and the recovery phase.
Journal ArticleDOI

A new functional form to study the solar wind control of the magnetopause size and shape

TL;DR: In this article, a new functional form, r = r 0 [2/(1 + cos θ)] α, is used to fit the size and shape of the magnetopause using crossings from ISEE 1 and 2, Active Magnetospheric Particle Tracer Explorers/Ion Release Module (AMPTE/IRM), and IMP 8 satellites.
Journal ArticleDOI

Transport of solar wind into Earth's magnetosphere through rolled-up Kelvin–Helmholtz vortices

TL;DR: It is shown that during northward solar-wind magnetic field conditions—in the absence of active reconnection at low latitudes—there is aSolar-wind transport mechanism associated with the nonlinear phase of the Kelvin–Helmholtz instability that can supply plasma sources for various space weather phenomena.
Journal ArticleDOI

The magnetotail and substorms

TL;DR: In this article, a phenomenological or qualitative model of the substorm sequence is presented, where the flux transport is driven by the merging of the magnetospheric and interplanetary magnetic fields.
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