Mirror mode structures in the asymmetric Hermean magnetosheath: Hybrid simulations

Herčík, David; Trávníček, Pavel; Johnson, Jay R.; Kim, Eun Hwa; Hellinger, Petr

doi:10.1029/2012ja018083

Cited by 28 publications

(25 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, when considering planetary heavy ions with their gyroradii comparable to Mercury's radius, individual ion motion needs to be taken into account. Both hybrid (Fatemi et al., 2018; Herčík et al., 2013; Müller et al., 2012; Parunakian et al., 2017; Richer et al., 2012; Trávníček et al., 2010) and magnetohydrodynamics (MHD) models (Jia et al., 2015, 2019; Pantellini et al., 2015; Varela et al., 2016; Yagi et al., 2010) have been applied to describe solar wind dynamics near Mercury. As we analyze the feedback of exospheric sodium ions onto Mercury's magnetosphere, which have a pickup gyroradius of about 2.4 R M , the application of a hybrid model is indeed mandatory.…”

Section: Hybrid Model Aikefmentioning

confidence: 99%

Influence of Mercury's Exosphere on the Structure of the Magnetosphere

et al. 2020

View full text Add to dashboard Cite

Mercury is embedded in a tenuous and highly anisotropic sodium exosphere, generated mainly by plasma‐surface interactions. The absolute values of the sodium ion density are still under debate. Observations by MESSENGER's Fast Imaging Plasma Spectrometer (FIPS) instrument suggest the density of exospheric ions to be several orders of magnitude lower than the upstream solar wind density, indicating that the sodium exosphere has no substantial influence on the magnetospheric current systems. However, MESSENGER magnetic field observations of field line resonances revealed sodium ion densities comparable to the upstream solar wind density. To investigate how a dense exosphere would affect the current systems within Mercury's magnetosphere, we apply an established hybrid (kinetic ions, fluid electrons) model and conduct multiple model runs with gradually increasing exospheric density, ranging from no sodium ions at all to comet‐like configurations. We demonstrate how a sufficiently dense exosphere leads to self‐shielding of the sodium ion population from the ambient electric field and a significant inflation and symmetrization of Mercury's magnetosphere, which is decreasingly affected by the dipole offset. Once the sodium ion density is sufficiently high, Region 2 field‐aligned currents emerge close to the planet. The modeled Region 2 currents are located below the orbit of MESSENGER, thereby providing a possible explanation for the absence of these currents in observations. The sodium exosphere also closes a significant fraction of the Region 1 currents through Pedersen and Hall currents before the “guiding” magnetic field lines even reach the planetary surface. The modeled sodium ion and solar wind densities agree well with observations.

show abstract

Section: Hybrid Model Aikefmentioning

confidence: 99%

Influence of Mercury's Exosphere on the Structure of the Magnetosphere

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The mirror instability is usually investigated in homogeneous or weakly inhomogeneous plasmas (Hasegawa 1969;Hellinger 2008;Herčík et al 2013). Behavior of this instability is a strongly turbulent (and strongly inhomogeneous) plasma such as the solar wind one is an open problem.…”

Section: Introductionmentioning

confidence: 99%

Mirror Instability in the Turbulent Solar Wind

Hellinger

Landi

Matteini

et al. 2017

ApJ

Self Cite

View full text Add to dashboard Cite

The relationship between a decaying strong turbulence and the mirror instability in a slowly expanding plasma is investigated using two-dimensional hybrid expanding box simulations. We impose an initial ambient magnetic field perpendicular to the simulation box, and we start with a spectrum of large-scale, linearly-polarized, random-phase Alfvénic fluctuations which have energy equipartition between kinetic and magnetic fluctuations and vanishing correlation between the two fields. A turbulent cascade rapidly develops, magnetic field fluctuations exhibit a Kolmogorov-like power-law spectrum at large scales and a steeper spectrum at sub-ion scales. The imposed expansion (taking a strictly transverse ambient magnetic field) leads to generation of an important perpendicular proton temperature anisotropy that eventually drives the mirror instability. This instability generates large-amplitude, nonpropagating, compressible, pressure-balanced magnetic structures in a form of magnetic enhancements/humps that reduce the perpendicular temperature anisotropy.

show abstract

“…Previously, mirror modes have been studied in a global simulation by Herčík et al [] who used 3‐D hybrid particle‐in‐cell (PIC) simulation. They simulated a down‐scaled Hermean magnetosphere during both southward and northward IMF.…”

Section: Introductionmentioning

confidence: 99%

Mirror modes in the Earth's magnetosheath: Results from a global hybrid‐Vlasov simulation

et al. 2016

View full text Add to dashboard Cite

We investigate mirror mode structures in the Earth's magnetosheath using our global kinetic Vlasiator simulation, which models ion behavior through their distribution function and treats electrons as a charge‐neutralizing fluid. We follow the evolution of waves as they advect along velocity streamlines through the magnetosheath. We find that mirror mode waves are observed preferentially in the quasi‐perpendicular magnetosheath along velocity streamlines that enter the sheath in the vicinity of the foreshock ULF wave boundary where there are enough initial perturbations in the plasma for the mirror modes to grow, and the plasma properties fulfill the mirror instability condition better than elsewhere in the magnetosheath. We test selection criteria defined by previous studies and show that the spatial extent over which mirror modes occur ranges from much of the magnetosheath on the quasi‐perpendicular side of the subsolar point to very small isolated regions depending on the criteria.

show abstract

Mirror mode structures in the asymmetric Hermean magnetosheath: Hybrid simulations

Cited by 28 publications

References 64 publications

Influence of Mercury's Exosphere on the Structure of the Magnetosphere

Influence of Mercury's Exosphere on the Structure of the Magnetosphere

Mirror Instability in the Turbulent Solar Wind

Mirror modes in the Earth's magnetosheath: Results from a global hybrid‐Vlasov simulation

Contact Info

Product

Resources

About