scholarly journals Ion dynamics during compression of Mercury's magnetosphere

2010 ◽  
Vol 28 (8) ◽  
pp. 1467-1474 ◽  
Author(s):  
D. C. Delcourt ◽  
T. E. Moore ◽  
M.-C. H. Fok
Keyword(s):  
Magnetic Field ◽  
Energetic Material ◽  
Three Dimensional ◽  
Wind Pressure ◽  
Field Variation ◽  
Ion Dynamics ◽  
Ion Energization ◽  
Particle Simulations ◽  
Solar Wind Pressure ◽  
Planetary Magnetic Field

Abstract. Because of the small planetary magnetic field as well as proximity to the Sun that leads to enhanced solar wind pressure as compared to Earth, the magnetosphere of Mercury is very dynamical and at times subjected to prominent compression. We investigate the dynamics of magnetospheric ions during such compression events. Using three-dimensional single-particle simulations, we show that the electric field induced by the time varying magnetic field can lead to significant ion energization, up to several hundreds of eVs or a few keVs. This energization occurs in a nonadiabatic manner, being characterized by large enhancements of the ion magnetic moment and bunching in gyration phase. It is obtained when the ion cyclotron period is comparable to the field variation time scale. This condition for nonadiabatic heating is realized in distinct regions of space for ions with different mass-to-charge ratios. During compression of Mercury's magnetosphere, heavy ions originating from the planetary exosphere may be subjected to such an abrupt energization, leading to loading of the magnetospheric lobes with energetic material.

scholarly journals On the effect of IMF turning on ion dynamics at Mercury

2011 ◽  
Vol 29 (6) ◽  
pp. 987-996 ◽  
Author(s):  
D. C. Delcourt ◽  
T. E. Moore ◽  
M.-C. H. Fok
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Energetic Material ◽  
Three Dimensional ◽  
Circulation Pattern ◽  
Field Variation ◽  
Ion Dynamics ◽  
Magnetic Field Model ◽  
Particle Simulations ◽  
The Imf

Abstract. We investigate the effect of a rotation of the Interplanetary Magnetic Field (IMF) on the transport of magnetospheric ion populations at Mercury. We focus on ions of planetary origin and investigate their large-scale circulation using three-dimensional single-particle simulations. We show that a nonzero BX component of the IMF leads to a pronounced asymmetry in the overall circulation pattern. In particular, we demonstrate that the centrifugal acceleration due to curvature of the E × B drift paths is more pronounced in one hemisphere than the other, leading to filling of the magnetospheric lobes and plasma sheet with more or less energetic material depending upon the hemisphere of origin. Using a time-varying electric and magnetic field model, we investigate the response of ions to rapid (a few tens of seconds) re-orientation of the IMF. We show that, for ions with gyroperiods comparable to the field variation time scale, the inductive electric field should lead to significant nonadiabatic energization, up to several hundreds of eVs or a few keVs. It thus appears that IMF turning at Mercury should lead to localized loading of the magnetosphere with energetic material of planetary origin (e.g., Na+).

scholarly journals Planetary magnetic field control of ion escape from weakly magnetized planets

2019 ◽  
Vol 488 (2) ◽  
pp. 2108-2120 ◽  
Author(s):  
Hilary Egan ◽  
Riku Jarvinen ◽  
Yingjuan Ma ◽  
David Brain
Keyword(s):  
Magnetic Field ◽  
Effective Interaction ◽  
Three Dimensional ◽  
Power Laws ◽  
Wind Pressure ◽  
Escape Rate ◽  
Opening Angle ◽  
Plasma Environment ◽  
Ion Escape ◽  
Planetary Magnetic Field

ABSTRACT Intrinsic magnetic fields have long been thought to shield planets from atmospheric erosion via stellar winds; however, the influence of the plasma environment on atmospheric escape is complex. Here we study the influence of a weak intrinsic dipolar planetary magnetic field on the plasma environment and subsequent ion escape from a Mars-sized planet in a global three-dimensional hybrid simulation. We find that increasing the strength of a planet’s magnetic field enhances ion escape until the magnetic dipole’s standoff distance reaches the induced magnetosphere boundary. After this point increasing the planetary magnetic field begins to inhibit ion escape. This reflects a balance between shielding of the Southern hemisphere from ‘misaligned’ ion pickup forces and trapping of escaping ions by an equatorial plasmasphere. Thus, the planetary magnetic field associated with the peak ion escape rate is critically dependent on the stellar wind pressure. Where possible we have fit power laws for the variation of fundamental parameters (escape rate, escape power, polar cap opening angle, and effective interaction area) with magnetic field, and assessed upper and lower limits for the relationships.

scholarly journals Solar wind and substorm excitation of the wavy current sheet

2009 ◽  
Vol 27 (6) ◽  
pp. 2457-2474 ◽  
Author(s):  
C. Forsyth ◽  
M. Lester ◽  
R. C. Fear ◽  
E. Lucek ◽  
I. Dandouras ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Current Sheet ◽  
Pressure Pulse ◽  
Wind Pressure ◽  
Expansion Velocity ◽  
Solar Wind Pressure ◽  
Wave Models ◽  
Best Fit ◽  
The Magnetic Field

Abstract. Following a solar wind pressure pulse on 3 August 2001, GOES 8, GOES 10, Cluster and Polar observed dipolarizations of the magnetic field, accompanied by an eastward expansion of the aurora observed by IMAGE, indicating the occurrence of two substorms. Prior to the first substorm, the motion of the plasma sheet with respect to Cluster was in the ZGSM direction. Observations following the substorms show the occurrence of current sheet waves moving predominantly in the −YGSM direction. Following the second substorm, the current sheet waves caused multiple current sheet crossings of the Cluster spacecraft, previously studied by Zhang et al. (2002). We further this study to show that the velocity of the current sheet waves was similar to the expansion velocity of the substorm aurora and the expansion of the dipolarization regions in the magnetotail. Furthermore, we compare these results with the current sheet wave models of Golovchanskaya and Maltsev (2005) and Erkaev et al. (2008). We find that the Erkaev et al. (2008) model gives the best fit to the observations.

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.

scholarly journals Rosetta and Mars Express observations of the influence of high solar wind pressure on the Martian plasma environment

2009 ◽  
Vol 27 (12) ◽  
pp. 4533-4545 ◽  
Author(s):  
N. J. T. Edberg ◽  
U. Auster ◽  
S. Barabash ◽  
A. Bößwetter ◽  
D. A. Brain ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Pressure ◽  
Solar Wind ◽  
Pressure Pulse ◽  
Wind Pressure ◽  
Data Set ◽  
Mars Express ◽  
Boundary Crossings ◽  
Plasma Environment ◽  
Solar Wind Pressure

Abstract. We report on new simultaneous in-situ observations at Mars from Rosetta and Mars Express (MEX) on how the Martian plasma environment is affected by high pressure solar wind. A significant sharp increase in solar wind density, magnetic field strength and turbulence followed by a gradual increase in solar wind velocity is observed during ~24 h in the combined data set from both spacecraft after Rosetta's closest approach to Mars on 25 February 2007. The bow shock and magnetic pileup boundary are coincidently observed by MEX to become asymmetric in their shapes. The fortunate orbit of MEX at this time allows a study of the inbound boundary crossings on one side of the planet and the outbound crossings on almost the opposite side, both very close to the terminator plane. The solar wind and interplanetary magnetic field (IMF) downstream of Mars are monitored through simultaneous measurements provided by Rosetta. Possible explanations for the asymmetries are discussed, such as crustal magnetic fields and IMF direction. In the same interval, during the high solar wind pressure pulse, MEX observations show an increased amount of escaping planetary ions from the polar region of Mars. We link the high pressure solar wind with the observed simultaneous ion outflow and discuss how the pressure pulse could also be associated with the observed boundary shape asymmetry.

Automatic detection of magnetopause and bow shock crossing signatures in MESSENGER magnetometer data using Convolutional Neural Networks.

2021 ◽  
Author(s):  
Alexander Lavrukhin ◽  
David Parunakian ◽  
Dmitry Nevskiy ◽  
Sahib Julka ◽  
Michael Granitzer ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Bow Shock ◽  
Cycle Phase ◽  
Small Subset ◽  
Magnetometer Data ◽  
Spacecraft Mission ◽  
Planetary Magnetic Field

<p>During its 2011-2015 lifetime the MESSENGER spacecraft completed more than 4000 orbits around Mercury, producing vast amounts of information regarding the planetary magnetic field and magnetospheric processes. During each orbit the spacecraft left and re-entered the Hermean magnetosphere, giving us information about more than 8000 crossings of the bow shock and the magnetopause of Mercury's magnetosphere. The information obtained from the magnetometer data offers the possibility to study in depth the structures of the bow shock and magnetopause current sheets and their shapes. In this work, we take a step in this direction by automatically detecting the crossings of bow-shock and magnetopause. To this end, we propose a five-class problem and train a Convolutional Neural Network based classifier using the magnetometer data. Our key experimental results indicate that an average precision and recall of at least 87% and 96% can be achieved on the bow hock and magnetopause crossings by using only a small subset of the data. We also model the average three-dimensional shape of these boundaries depending on the external interplanetary magnetic field . Furthermore, we attempt to clarify the dependence of the two boundary locations on the heliocentric distance of Mercury and on the solar activity cycle phase. This work may be of particular interest for future Mercury research related to the BepiColombo spacecraft mission, which will enter Mercury’s orbit around December 2025.</p>

Characteristics and variability of Titan's magnetic environment

2008 ◽  
Vol 367 (1889) ◽  
pp. 789-798 ◽  
Author(s):  
César L Bertucci
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Current Sheet ◽  
Radial Component ◽  
Wind Pressure ◽  
Rotation Direction ◽  
Background Magnetic Field ◽  
Solar Wind Pressure ◽  
Field Lines ◽  
The Magnetic Field

The structure and variability of Saturn's magnetic field in the vicinity of Titan's orbit is studied. In the dawn magnetosphere, the magnetic field presents a significant radial component directed towards Saturn, suggesting that Titan is usually located below the planet's warped and dynamic magnetodisc. Also, a non-negligible component along the co-rotation direction suggests that Saturn's magnetic field lines close to the magnetodisc are being swept back from their respective magnetic meridians. In the noon sector, Titan seems to be closer to the magnetodisc central current sheet, as the field lines in this region seem to be more dipolar. The distance between the central current sheet and Titan depends mainly on the solar wind pressure. Also, δ | B |/| B |∼0.5 amplitude waveforms at periods close to Saturn's kilometric radiation period are present in the background magnetic field. This modulation in the field is ubiquitous in Saturn's magnetosphere and associated with the presence of a rotating asymmetry in the planet's magnetic field.

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