scholarly journals Spatially Highly Resolved Solar-wind-induced Magnetic Field on Venus

2021 ◽  
Vol 923 (1) ◽  
pp. 73
Author(s):  
Maosheng He ◽  
Joachim Vogt ◽  
Eduard Dubinin ◽  
Tielong Zhang ◽  
Zhaojin Rong
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
High Spatial Resolution ◽  
Field Structure ◽  
Induced Magnetic Field ◽  
Opposite Hemisphere ◽  
Narrow Region ◽  
Least Squares Fit ◽  
Cylindrical Coordinate ◽  
Induced Field

Abstract The current work investigates the Venusian solar-wind-induced magnetosphere at a high spatial resolution using all Venus Express (VEX) magnetic observations through an unbiased statistical method. We first evaluate the predictability of the interplanetary magnetic field (IMF) during VEX’s Venusian magnetospheric transits and then map the induced field in a cylindrical coordinate system under different IMF conditions. Our mapping resolves structures on various scales, ranging from the ionopause to the classical IMF draping. We also resolve two recently reported structures, a low-ionosphere magnetization over the terminator, and a global “looping” structure in the near magnetotail. In contrast to the reported IMF-independent cylindrical magnetic field of both structures, our results illustrate their IMF dependence. In both structures, the cylindrical magnetic component is more intense in the hemisphere with an upward solar wind electric field (E SW) than in the opposite hemisphere. Under downward E SW, the looping structure even breaks, which is attributable to an additional draped magnetic field structure wrapping toward −E SW. In addition, our results suggest that these two structures are spatially separate. The low-ionosphere magnetization occurs in a very narrow region, at about 88°–95° solar zenith angle and 185–210 km altitude. A least-squares fit reveals that this structure is attributable to an antisunward line current with 191.1 A intensity at 179 ± 10 km altitude, developed potentially in a Cowling channel.

scholarly journals Europa's Alfvén wing: shrinkage and displacement influenced by an induced magnetic field

2007 ◽  
Vol 25 (4) ◽  
pp. 905-914 ◽  
Author(s):  
M. Volwerk ◽  
K. Khurana ◽  
M. Kivelson
Keyword(s):  
Magnetic Field ◽  
Plasma Density ◽  
Geometric Modeling ◽  
Numerical Models ◽  
Background Field ◽  
Entry And Exit ◽  
Induced Magnetic Field ◽  
Background Magnetic Field ◽  
Magnetometer Data ◽  
Induced Field

Abstract. The Galileo magnetometer data are used to investigate the structure of the Alfvén wing during three flybys of Europa. The presence of an induced magnetic field is shown to shrink the cross section of the Alfvén wing and offset it along the direction radial to Jupiter. Both the shrinkage and the offset depend on the strength of the induced field. The entry and exit points of the spacecraft into and out of the Alfvén wings are modeled to determine the angle between the wings and the background magnetic field. Tracing of the Alfvén characteristics in a model magnetic field consisting of Jupiter's background field and an induced field in Europa produces an offset and shrinking of the Alfvén wing consistent with the geometric modeling. Thus we believe that the Alfvén wing properties have been determined correctly. The Alfvén wing angle is directly proportional to the local Alfvén velocity, and is thus a probe for the local plasma density. We show that the inferred plasma density can be understood in terms of the electron density measured by the plasma wave experiment. When Europa is located in the Jovian plasma sheet the derived mass-per-charge exceeds the previous estimates, which is a result of increased pickup of sputtered ions near the moon. The estimated rate of O2+ pickup agrees well with the results from numerical models.

scholarly journals Induced and Permanent Magnetism on the Moon: Structural and Evolutionary Implications

1971 ◽  
Vol 2 ◽  
pp. 173-188
Author(s):  
C. P. Sonett ◽  
P. Dyal ◽  
D. S. Colburn ◽  
B. F. Smith ◽  
G. Schubert ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Dynamic Pressure ◽  
Wind Pressure ◽  
Dark Side ◽  
The Moon ◽  
Permanent Magnetic Field ◽  
Crustal Layer ◽  
Induced Field ◽  
Solar Wind Pressure

AbstractIt is shown that the Moon possesses an extraordinary response to induction from the solar wind due to a combination of a high interior electrical conductivity together with a relatively resistive crustal layer into which the solar wind dynamic pressure forces back the induced field. The dark side response, devoid of solar wind pressure, is approximately that expected for the vacuum case. These data permit an assessment of the interior conductivity and an estimate of the thermal gradient in the crustal region. The discovery of a large permanent magnetic field at the Apollo 12 site corresponds approximately to the paleomagnetic residues discovered in both Apollo 11 and 12 rock samples The implications regarding an early lunar magnetic field are discussed and it is shown that among the various conjectures regarding the early field the most prominent are either an interior dynamo or an early approach to the Earth though no extant model is free of difficulties.

Über stationäre, magnetogasdynamische Strömungen endlicher Ausdehnung

1968 ◽  
Vol 23 (12) ◽  
pp. 1940-1952
Author(s):  
K. Ragaller
Keyword(s):  
Magnetic Field ◽  
Finite Thickness ◽  
Two Dimensional ◽  
Finite Region ◽  
Induced Magnetic Field ◽  
Induced Field ◽  
Adjacent Field ◽  
Ambient Gas ◽  
Flow Variables ◽  
Flow Around A Body

Steady, two-dimensional, magnetogasdynamic flows in a finite region are investigated. In this paper the case of aligned fields is treated. Outside of the flow a resting gas with arbitrary electrical conductivity is assumed. As the induced magnetic field can propagate throughout the resting gas, all the flow is strongly influenced by this adjacent field-occupied region.This interaction between the field in the resting ambient gas and the flow can be formulated as an integral equation, the solution of which is given.In a number of examples the applicability of this formalism is demonstrated. So the flow around a body, the reflection of waves at a boundary, and the influence of an applied magnetic field, are investigated for a flow in the halfspace and for a jet of finite thickness. Besides the flow variables, the location of the boundary and the induced field outside of the flow, are calculated.

scholarly journals Spatial Variation in the Responses of the Surface External and Induced Magnetic Field to the Solar Wind

2019 ◽  
Vol 124 (7) ◽  
pp. 6195-6211 ◽  
Author(s):  
R. M. Shore ◽  
M. P. Freeman ◽  
J. C. Coxon ◽  
E. G. Thomas ◽  
J. W. Gjerloev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Spatial Variation ◽  
Induced Magnetic Field

A two-spacecraft study of Mars induced magnetosphere's response to upstream conditions

2020 ◽  
Author(s):  
Katerina Stergiopoulou ◽  
Niklas Edberg ◽  
David Andrews ◽  
Beatriz Sánchez-Cano
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Real Time ◽  
Dynamic Pressure ◽  
Local Magnetic Field ◽  
Mars Atmosphere ◽  
Solar Wind Magnetic Field ◽  
Magnetic Field Magnitude ◽  
Induced Field ◽  
The Imf

<p>We investigate the effects of the upstream solar wind magnetic field on the Martian induced magnetosphere. This is a two-spacecraft study, for which we use Mars Express (MEX) magnetic field magnitude data from the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument and Interplanetary Magnetic Field (IMF) measurements and solar wind density and velocity from the magnetometer (MAG) and the Solar Wind Ion Analyzer (SWIA) on board Mars Atmosphere and Volatile EvolutioN (MAVEN), from November 2014 to November 2018. Equally temporally spaced echoes appear in MARSIS' ionograms from which the electron cyclotron frequency and eventually the magnitude of the local magnetic field can be calculated. At the same time solar wind magnetic field data and solar wind parameters from MAG and SWIA respectively are utilized, providing the solar wind input to the Martian system. We make real time comparisons of the IMF and the induced magnetic field in the environment of Mars and we test the ratio B<sub>(MEX)</sub> /B<sub>(MAVEN)</sub>  against various parameters such as the solar wind dynamic pressure, velocity, density, Mach number as well as the Martian seasons, latitudes and heliocentric distances. Additionally, we search for disturbances in IMF which then can be traced in the induced field ultimately revealing the response time of the induced magnetosphere to the solar wind behaviour. <br />MEX and MAVEN measurements combined allow us to investigate the response of the Martian induced magnetosphere to the solar wind magnetic field. Real time comparisons of the IMF and the induced field could help us understand the mechanisms controlling the structure of the Martian induced magnetosphere. </p>

scholarly journals An interpretation for the bipolar electric field structures parallel to the magnetic field observed in the auroral ionosphere

2008 ◽  
Vol 26 (6) ◽  
pp. 1431-1437 ◽  
Author(s):  
◽  
M. N. S. Qureshi ◽  
K. Torkar ◽  
M. Dunlop ◽  
T. L. Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Fluid Model ◽  
Field Structure ◽  
Auroral Ionosphere ◽  
Ion Acoustic Wave ◽  
Cylindrical Coordinate ◽  
Two Fluid Model ◽  
The Magnetic Field ◽  
Two Fluid

Abstract. A physical model for the existence of bipolar structures in the electric field that are parallel to the magnetic field and observed in the auroral ionosphere, is established by deriving the "Sagdeev potential" from the two-fluid equations in a cylindrical coordinate system. The model shows that the bipolar electric field structure can develop not only from an ion acoustic wave, but also from an ion cyclotron wave, when the Mach number and the initial electric field satisfy certain conditions. Moreover, in the auroral region, it shows that the polarity of this electric field structure can be oriented either negative to positive or the reverse polarity, its amplitude can be varied from 35 to 330 mV/m, and its duration can be 7 ms to 23 ms. These results are in agreement with observation. Therefore, our two-fluid model can interpret the bipolar structures observed in the auroral ionosphere.

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