EVIDENCE FOR QUASI-ADIABATIC MOTION OF CHARGED PARTICLES IN STRONG CURRENT SHEETS IN THE SOLAR WIND

BepiColombo is going to conduct its first Mercury flyby in October 2021. During this flyby,&#160; plasma measurement will be obtained and bring new insights on the Hermean magnetosphere and its interaction with the Sun despite the limited field of view of the instruments during the cruise phase. Unlike Mariner-10 ion measurements will be obtained, and unlike MESSENGER, low energy electrons and ions will be measured simultaneously. In this study, we have revisited Mariner 10 and MESSENGER observations with the help of the global hybrid model LatHyS in order to understand the influence of time-variable solar wind and to constraint the plasma environment. We are able to reproduce the magnetic field observations of Mariner 10 along its trajectory with in particular two distinct signatures consisting of a quiet and disturbed state of the magnetosphere. In addition, the plasma spectrogram is also collected in the model and this enables us to detail the properties of the charged particles observed during the flyby. We will discuss all these signatures both in term of an interaction with a time-variable solar wind and localized processes occurring in the magnetosphere. We will then present the virtual sampling of both the magnetic field and plasma spectrogram along BepiColombo&#8217;s first Mercury flyby trajectory and discuss the possible signatures to be observed at that time.

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Solar Orbiter observations of solar wind current sheets and their deHoffman-Teller frames

10.5194/egusphere-egu21-10630 ◽

2021 ◽

Author(s):

Konrad Steinvall ◽

Yuri Khotyaintsev ◽

Giulia Cozzani ◽

Andris Vaivads ◽

Christopher Owen ◽

...

Keyword(s):

Solar Wind ◽

Electric Field ◽

Wind Velocity ◽

Solar Wind Velocity ◽

Field Measurements ◽

Velocity Measurements ◽

Current Sheets ◽

Spacecraft Orbit ◽

Electric Field Measurements ◽

Good Agreement

Solar wind current sheets have been extensively studied at 1 AU. The recent advent of Parker Solar Probe and Solar Orbiter (SolO) has enabled us to study these structures at a range of heliocentric distances.We present SolO observations of current sheets in the solar wind at heliocentric distances between 0.55 and 0.85 AU, some of which show signatures of ongoing magnetic reconnection. We develop a method to find the deHoffman-Teller frame which minimizes the Y-component (the component tangential to the spacecraft orbit) of the electric field. Using the electric field measurements from RPW and magnetic field measurements from MAG, we use our method to determine the deHoffman-Teller frame of solar wind current sheets. The same method can also be used on the Alfv&#233;nic turbulence and structures found in the solar wind to obtain a measure of the solar wind velocity.Our preliminary results show a good agreement between our modified deHoffmann-Teller analysis based on the single component E-field, and the conventional deHoffman-Teller analysis based on 3D plasma velocity measurements from PAS. This opens up the possibility to use the RPW and MAG data to obtain an estimate of the solar wind velocity when particle data is unavailable.

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Ultrahigh-resolution model of a breakout CME embedded in the solar wind

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832976 ◽

2018 ◽

Vol 620 ◽

pp. A57 ◽

Cited By ~ 5

Author(s):

S. Hosteaux ◽

E. Chané ◽

B. Decraemer ◽

D.-C. Talpeanu ◽

S. Poedts

Keyword(s):

Solar Wind ◽

Adaptive Mesh Refinement ◽

Flux Rope ◽

Adaptive Mesh ◽

Electrical Current ◽

Substantial Effect ◽

Small Scale ◽

Release Process ◽

Ultrahigh Resolution ◽

Current Sheets

Aims. We investigate the effect of a background solar wind on breakout coronal mass ejections, in particular, the effect on the different current sheets and the flux rope formation process. Methods. We obtained numerical simulation results by solving the magnetohydrodynamics equations on a 2.5D (axisymmetric) stretched grid. Ultrahigh spatial resolution is obtained by applying a solution adaptive mesh refinement scheme by increasing the grid resolution in regions of high electrical current, that is, by focussing on the maximum resolution of the current sheets that are forming. All simulations were performed using the same initial base grid and numerical schemes; we only varied the refinement level. Results. A background wind that causes a surrounding helmet streamer has been proven to have a substantial effect on the current sheets that are forming and thus on the dynamics and topology of the breakout release process. Two distinct ejections occur: first, the top of the helmet streamer detaches, and then the central arcade is pinched off behind the top of the helmet streamer. This is different from the breakout scenario that does not take the solar wind into account, where only the central arcade is involved in the eruption. In the new ultrahigh-resolution simulations, small-scale structures are formed in the lateral current sheets, which later merge with the helmet streamer or reconnect with the solar surface. We find that magnetic reconnections that occur at the lateral breakout current sheets deliver the major kinetic energy contribution to the eruption and not the reconnection at the so-called flare current sheet, as was seen in the case without background solar wind.

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Extreme value theory in the solar wind: the role of current sheets

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2668 ◽

2019 ◽

Vol 490 (2) ◽

pp. 1879-1893

Author(s):

Tiago F P Gomes ◽

Erico L Rempel ◽

Fernando M Ramos ◽

Suzana S A Silva ◽

Pablo R Muñoz

Keyword(s):

Solar Wind ◽

Power Spectra ◽

Value Theory ◽

Extreme Value ◽

Extreme Value Statistics ◽

Intermittent Turbulence ◽

Current Sheets ◽

Developed Turbulence ◽

The Right

ABSTRACT This article provides observational evidence for the direct relation between current sheets, multifractality and fully developed turbulence in the solar wind. In order to study the role of current sheets in extreme-value statistics in the solar wind, the use of magnetic volatility is proposed. The statistical fits of extreme events are based on the peaks-over-threshold (POT) modelling of Cluster 1 magnetic field data. The results reveal that current sheets are the main factor responsible for the behaviour of the tail of the magnetic volatility distributions. In the presence of current sheets, the distributions display a positive shape parameter, which means that the distribution is unbounded in the right tail. Thus the appearance of larger current sheets is to be expected and magnetic reconnection events are more likely to occur. The volatility analysis confirms that current sheets are responsible for the −5/3 Kolmogorov power spectra and the increase in multifractality and non-Gaussianity in solar wind statistics. In the absence of current sheets, the power spectra display a −3/2 Iroshnikov–Kraichnan law. The implications of these findings for the understanding of intermittent turbulence in the solar wind are discussed.

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