Current sheets at low altitudes in the Martian magnetotail

Halekas, J. S.; Brain, David; Lillis, Robert J.; Fillingim, M. O.; Mitchell, David; Lin, R. P.

doi:10.1029/2006gl026229

Cited by 62 publications

(65 citation statements)

References 17 publications

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“…Based on considerations of geometry, it seems more likely that these flux ropes are being generated sequentially at a single site rather than by the simultaneous formation of multiple X-lines. Although observations of this type are quite rare in MGS data, this event is not unique; in a database of 1116 MGS magnetotail current sheet crossings [Halekas et al, 2006], we have identified 45 examples where multiple flux ropes were observed, however the event presented here is the cleanest example.…”

Section: Discussionmentioning

confidence: 79%

“…The magnetotail is a region through which there is significant escape of ionospheric material [Lundin et al, 2008], and so it is important to ascertain the extent to which magnetotail dynamics may inhibit or enhance the transport of planetary plasma away from Mars. In particular, within the magnetotail is found the magnetotail current sheet, separating the two hemispheres of draped solar wind magnetic field [Halekas et al, 2006]. The interaction between crustal fields and the draped field can lead to the formation and detachment of large magnetic flux ropes enabling the bulk removal of material [Harnett, 2009;Brain et al, 2010;Morgan et al, 2011].…”

Section: Introductionmentioning

confidence: 99%

“…The sections of the |B| time series colored red are regions where crustal fields are thought to be present, based on existing models [Cain et al, 2003]. Between 14:45UT-14:55UT, B x reverses in sign, indicating a magnetotail current sheet crossing [Halekas et al, 2006]. [7] The current sheet crossing is shown in more detail in Figures 1e-1i.…”

Section: Introductionmentioning

confidence: 99%

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A chain of magnetic flux ropes in the magnetotail of Mars

Eastwood

Videira

Brain

et al. 2012

Geophysical Research Letters

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[1] The interaction of Mars with the solar wind leads to the formation of a magnetotail through which significant quantities of planetary plasma are transported. Of particular interest is the extent to which this plasma transport could be affected by magnetotail dynamics, for example by magnetic reconnection and flux rope formation. Here we show observations from Mars Global Surveyor of multiple flux ropes observed in Mars' magnetotail current sheet. A chain of at least three flux ropes is observed; based on the geometry of the encounter, the flux ropes are all being ejected in the same direction from a single dominant site and modeling shows that at least two of the flux ropes are close to being in a force free condition. Given geometrical considerations, it is likely that the flux ropes are generated sequentially rather than simultaneously, suggesting periodic generation via secondary instabilities at the reconnection site. Citation: Eastwood, J. P., J. J. H. Videira, D. A. Brain, and J. S. Halekas (2012), A chain of magnetic flux ropes in the magnetotail of Mars, Geophys. Res. Lett., 39, L03104,

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Section: Discussionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A chain of magnetic flux ropes in the magnetotail of Mars

Eastwood

Videira

Brain

et al. 2012

Geophysical Research Letters

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“…The presence of field aligned currents have been infered from observations of perturbations in the magnetic field near magnetic cusps Halekas et al, 2006). The magnitude of these currents are ∼0.5 to 1 μA m −2 .…”

Section: Discussionmentioning

confidence: 99%

On wind-driven electrojets at magnetic cusps in the nightside ionosphere of Mars

Fillingim¹,

Lillis²,

England³

et al. 2012

Earth Planet Sp

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Mars has a complex magnetic topology where crustal magnetic fields can interact with the solar wind magnetic field to form magnetic cusps. On the nightside, solar wind electron precipitation can produce enhanced ionization at cusps while closed field regions adjacent to cusps can be devoid of significant ionization. Using an electron transport model, we calculate the spatial structure of the nightside ionosphere of Mars using Mars Global Surveyor electron measurements as input. We find that localized regions of enhanced ionospheric density can occur at magnetic cusps adjacent to low density regions. Under this configuration, thermospheric winds can drive ionospheric electrojets. Collisional ions move in the direction of the neutral winds while magnetized electrons move perpendicular to the wind direction. This difference in motion drives currents and can lead to charge accumulation at the edges of regions of enhanced ionization. Polarization fields drive secondary currents which can reinforce the primary currents leading to electrojet formation. We estimate the magnitude of these electrojets and show that their magnetic perturbations can be detectable from both orbiting spacecraft and the surface. The magnitude of the electrojets can vary on diurnal and annual time scales as the strength and direction of the winds vary. These electrojets may lead to localized Joule heating, and closure of these currents may require field-aligned currents which may play a role in high altitude acceleration processes.

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“…For the smaller bodies, Mars and Titan, the grid size is often smaller than the ion skin depth and boundary layers of the interaction can be resolved. For example, the thickness of the bow shock and magnetic pile-up boundary at Mars and Venus are on the order of the ion skin depth (Mazelle et al 2004) as is the current sheet thickness at Titan and Mars (Halekas et al 2006;Wahlund et al 2005). However, resolving the ion skin depth violates the assumptions of some models.…”

Section: Assumptions Of Mhd Modelsmentioning

confidence: 99%

Modeling of Venus, Mars, and Titan

et al. 2011

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Increased computer capacity has made it possible to model the global plasma and neutral dynamics near Venus, Mars and Saturn's moon Titan. The plasma interactions at Venus, Mars, and Titan are similar because each possess a substantial atmosphere but lacks a global internally generated magnetic field. In this article three self-consistent plasma models are described: the magnetohydrodynamic (MHD) model, the hybrid model and the fully kinetic plasma model. are also described. In particular, we describe the pros and cons of each model approach. Results from simulations are presented to demonstrate the ability of the models to capture the known plasma and neutral dynamics near the three objects.

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Current sheets at low altitudes in the Martian magnetotail

Cited by 62 publications

References 17 publications

A chain of magnetic flux ropes in the magnetotail of Mars

A chain of magnetic flux ropes in the magnetotail of Mars

On wind-driven electrojets at magnetic cusps in the nightside ionosphere of Mars

Modeling of Venus, Mars, and Titan

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