A Statistical Study of the Force Balance and Structure in the Flux Ropes in Mercury's Magnetotail

Zhao, Jiutong; Sun, W.; Zong, Qiugang; Slavin, J. A.; Zhou, X.‐Z.; Dewey, R. M.; Poh, Gangkai; Raines, J. M.

doi:10.1029/2018ja026329

Cited by 10 publications

(9 citation statements)

References 70 publications

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“…In the magnetotail lobes, more instances of magnetotail loading-unloading have been recorded postmidnight than pre-midnight (Imber and Slavin, 2017). Within the plasma sheet, dipolarizations (Sun et al, 2016;Dewey et al, 2020) and flux ropes (Sun et al, 2016;Smith et al, , 2018bZhao et al, 2019) are more abundant at dawn as measured either by event frequency or by the number of MESSENGER orbits that observed these events. As magnetotail reconnection produces these events (e.g., Slavin et al, 2012a;DiBraccio et al, 2015a;Dewey et al, 2020), their cross-tail asymmetry is indicative of the dawnside preference in Mercury's magnetotail reconnection (Sun et al, 2016;Smith et al, 2018b).…”

Section: Magnetotail Reconnection Dynamicsmentioning

confidence: 99%

Review of Mercury’s dynamic magnetosphere: Post-MESSENGER era and comparative magnetospheres

Sun

Dewey

Aizawa

et al. 2021

Sci. China Earth Sci.

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This review paper summarizes the research of Mercury’s magnetosphere in the Post-MESSENGER era and compares its dynamics to those in other planetary magnetospheres, especially to those in Earth’s magnetosphere. This review starts by introducing the planet Mercury, including its interplanetary environment, magnetosphere, exosphere, and conducting core. The frequent and intense magnetic reconnection on the dayside magnetopause, which is represented by the flux transfer event “shower”, is reviewed on how they depend on magnetosheath plasma β and magnetic shear angle across the magnetopause, following by how it contributes to the flux circulation and magnetosphere-surface-exosphere coupling. In the next, Mercury’s magnetosphere under extreme solar events, including the core induction and the reconnection erosion on the dayside magnetosphere, the responses of the nightside magnetosphere, are reviewed. Then, the dawn-dusk properties of the plasma sheet, including the features of the ions, the structure of the current sheet, and the dynamics of magnetic reconnection, are summarized. The last topic is devoted to the particle energization in Mercury’s magnetosphere, which includes the energization of the Kelvin-Helmholtz waves on the magnetopause boundaries, reconnection-generated magnetic structures, and the cross-tail electric field. In each chapter, the last section discusses the open questions related to each topic, which can be considered by the simulations and the future spacecraft mission. We end this paper by summarizing the future BepiColombo opportunities, which is a joint mission of ESA and JAXA and is en route to Mercury.

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Section: Magnetotail Reconnection Dynamicsmentioning

confidence: 99%

Review of Mercury’s dynamic magnetosphere: Post-MESSENGER era and comparative magnetospheres

Sun

Dewey

Aizawa

et al. 2021

Sci. China Earth Sci.

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“…The magnetic flux loading‐unloading process in Mercury's magnetosphere, that is, the magnetospheric substorm, has a time scale of only 2 to 3 min (Imber & Slavin, 2017; Slavin et al, 2010; Sun et al, 2015), which is caused by the low solar wind Alfvén Mach number (Slavin & Holzer, 1979; Scurry et al, 1994) and the small magnetosphere (Siscoe et al, 1975). The low solar wind Alfvén Mach number also produces many magnetic reconnection‐generated structures in the magnetosphere, including flux transfer events near the magnetopause (Russell & Walker, 1985; Slavin et al, 2009), flux ropes (DiBraccio, Slavin, Imber, et al, 2015; Slavin et al, 2012; Sun et al, 2016; Smith et al, 2018; Zhao et al, 2019), and dipolarization fronts in the magnetotail plasma sheet (Sundberg et al, 2012; Sun et al, 2016, 2018). These magnetic structures at Mercury resemble those at Earth, but they contain strong kinetic features.…”

Section: Introductionmentioning

confidence: 99%

Proton Properties in Mercury's Magnetotail: A Statistical Study

Zhao

Zong

Slavin

et al. 2020

Geophysical Research Letters

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This study investigates the properties of protons in the magnetotail plasma sheet of Mercury. By superposing 5-year measurements from the MESSENGER spacecraft, we obtain the average energy spectrum of protons in the plasma sheet, which can be fitted nicely by the Gaussian-Kappa model. The proton density, pressure, and energy spectral index are found to be higher on the dawnside than on the duskside. The proton temperature shows a clearly outward radial gradient. The field-aligned density profile indicates that the protons in the outer plasma sheet move adiabatically. The pitch angle distribution reveals the reflected fluxes to be always less than the incident fluxes and indicates the loss of protons due to their impact on the planetary surface. Plain Language Summary Mercury has a miniature magnetosphere subject to intense solar wind forcing. This magnetosphere, among the smallest in the solar system, resembles the Earth's in many key respects. It is also an analog for other small and outside-driven magnetospheres, such as Ganymede's inside Jupiter's magnetosphere. Mercury does not have a significant atmosphere but a tenuous exosphere. Therefore, Mercury's magnetospheric ions are thought to come predominately from the solar wind, and only about 10% of the ions are of planetary origin. This study presents a statistical picture of the protons in Mercury's magnetotail plasma sheet measured by the Fast Imaging Plasma Spectrometer (FIPS) onboard MESSENGER spacecraft. Many parameters are obtained through a best fit procedure with a Gaussian-Kappa distribution. The proton number density, proton pressure, and spectral index show clear dawn-dusk asymmetric features. The results also suggest that the motion of the protons is adiabatic in the outer plasma sheet and non-adiabatic in the central plasma sheet. Furthermore, the loss feature of the protons is also revealed by their asymmetric pitch angle distributions.

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“…During severe solar wind conditions, Mercury's dayside magnetosphere may even disappear 13,14 . Recent observations of MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) confirmed that Mercury's magnetosphere resembles Earth's in many aspects, such as magnetospheric structures (e.g., magnetotail, plasma mantle, and polar cusp), magnetospheric dynamic processes (e.g., flux loading-unloading, substorm dipolarizations), and magnetic structures (e.g., dipolarization fronts and flux ropes) [15][16][17][18] . However, in situ measurements to directly demonstrate the existence of Mercury's ring current are still lacking.…”

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confidence: 99%

Observational evidence of ring current in the magnetosphere of Mercury

et al. 2022

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The magnetic gradient and curvature drift of energetic ions can form a longitudinal electric current around a planet known as the ring current, that has been observed in the intrinsic magnetospheres of Earth, Jupiter, and Saturn. However, there is still a lack of observational evidence of ring current in Mercury’s magnetosphere, which has a significantly weaker dipole magnetic field. Under such conditions, charged particles are thought to be efficiently lost through magnetopause shadowing and/or directly impact the planetary surface. Here, we present the observational evidence of Mercury’s ring current by analysing particle measurements from MErcury Surface, Space Environment, GEochemistry, and Ranging (MESSENGER) spacecraft. The ring current is bifurcated because of the dayside off-equatorial magnetic minima. Test-particle simulation with Mercury’s dynamic magnetospheric magnetic field model (KT17 model) validates this morphology. The ring current energy exceeds $$5\times {10}^{10}$$ 5 × 10 10 J during active times, indicating that magnetic storms may also occur on Mercury.

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A Statistical Study of the Force Balance and Structure in the Flux Ropes in Mercury's Magnetotail

Cited by 10 publications

References 70 publications

Review of Mercury’s dynamic magnetosphere: Post-MESSENGER era and comparative magnetospheres

Review of Mercury’s dynamic magnetosphere: Post-MESSENGER era and comparative magnetospheres

Proton Properties in Mercury's Magnetotail: A Statistical Study

Observational evidence of ring current in the magnetosphere of Mercury

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