Magnetic Reconnection in the Martian Magnetotail: Occurrence Rate and Impact on Ion Loss

Wang, Lei; Huang, Can; Du, Aimin; Ge, Yasong; Chen, Guo; Fan, Jinqiao; Qin, Jipeng

doi:10.1029/2023gl104996

Cited by 4 publications

(2 citation statements)

References 67 publications

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“…For a purely induced magnetosphere excluding crustal fields, a 90°clock angle (i.e. B z = 0, B y > 0) results in the +B x and B x lobes on the dawn and dusk sides respectively, separated by a flat sheet-like structure known as the current sheet (within which cross-tail currents flow (Ramstad et al, 2020) and reconnection drives field-aligned currents (Harada et al, 2017;Wang et al, 2023)) oriented along the z-axis, in the same direction as the solar wind convection electric field (E conv = v sw × B IMF ), as shown clearly in Figure 3 of DiBraccio et al (2018). The opposite configuration, that is, +B x lobe on the dusk side of the tail, holds for a 270°clock angle (i.e.…”

Section: Imf Direction and Magnetotail Configurationmentioning

confidence: 99%

Sinuous Aurora at Mars: A Link to the Tail Current Sheet?

Lillis,

Deighan,

Chirakkil

et al. 2024

JGR Space Physics

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We examine the newly discovered phenomena of sinuous aurora on the nightside of Mars, using images of 130.4 and 135.6 nm oxygen emission measured by the Emirates Mars Mission EMUS ultraviolet spectrograph, and upstream measurements from the MAVEN and Mars Express spacecraft. They are detected in ∼3% of observations, totaling 73 clear detections. These emissions are narrow, elongated (1,000–6,000 km), cross Mars' UV terminator, and are oriented generally toward the anti‐solar point, clustering into north, south, east, and west‐oriented groups. Diverse morphologies are observed, though some spatial features, such as broad curves, may in some cases be due to temporal aliasing of aurora motion as each image is built up over 15–20 min. Sinuous aurora form away from Mars' strongest crustal magnetic fields and can be interrupted by moderate crustal fields. Sinuous aurora occurrence increases strongly with solar wind pressure, though brightness shows only a weak positive dependence on pressure. Interplanetary magnetic field (IMF) clock angle affects their occurrence and orientation: sinuous aurora show a broad range of orientations centered on the solar wind convection electric field (Econv) direction and forming in the +Econv hemisphere, although with moderate clockwise and counterclockwise average “twists” for westward and eastward IMF, respectively. From these features we infer a link between sinuous aurora and electron energization in Mars' magnetotail current sheet, where field geometry on the +Econv side of the sheet is more organized and symmetric. Determination of specific triggering conditions for sinuous aurora requires further investigation.

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Section: Imf Direction and Magnetotail Configurationmentioning

confidence: 99%

Sinuous Aurora at Mars: A Link to the Tail Current Sheet?

Lillis,

Deighan,

Chirakkil

et al. 2024

JGR Space Physics

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“…Nevertheless, when shifting our focus from the interplanetary plasmas to more various plasma environments, the role of the collision effect can be intriguing, for instance, in the lower solar atmosphere such as the photosphere and the chromosphere where neutral particles begin to take effect [28], and in the Martian magnetotail where dynamics of the heavy ions can affect the reconnection process effectively [29]. Moreover, magnetic reconnection in laboratory plasmas (e.g.…”

Section: Introductionmentioning

confidence: 99%

Hall physics during magnetic reconnection with collision effect

Shu,

Lu,

et al. 2024

Plasma Phys. Control. Fusion

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The Hall effect, decoupling between the ion and electron motions, is the core mechanism triggering fast reconnection. In plasmas with finite resistivity such as laboratory facilities, collision can suppress the Hall effect and influence the triggering of fast reconnection. Here, by conducting a series of kinetic simulations with varying collision parameters, we show that collisions can suppress the electron outflow, impairing the quadrupole Hall magnetic field. Besides, collision weakens the inflow of magnetic flux by reducing the charge separation and increasing the thermal pressure at the reconnection site, leading to a reduction of the Hall electric field. As the collisionality becomes larger, the Hall electric field diminishes more easily than the Hall magnetic field. We propose that the quadrupolar Hall magnetic field can be a significant indicator in reflecting Hall reconnection.

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Discrete aurora and the nightside ionosphere of Mars: an EMM–MEX conjunction of FUV imaging, ionospheric radar sounding, and suprathermal electron measurements

Harada,

Fujiwara,

Lillis

et al. 2024

Earth Planets Space

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Since 2021, a new surge in discrete aurora detections at Mars has been observed by the Emirates Mars Ultraviolet Spectrometer (EMUS) onboard the Emirates Mars Mission (EMM) Hope Orbiter as EMUS started to regularly obtain synoptic auroral images with a high sensitivity. Here we report on a fortuitous conjunction between EMM and Mars Express (MEX) using far ultraviolet (FUV) imaging of discrete aurora by EMM EMUS, in situ measurements of suprathermal electrons by the MEX Analyzer of Space Plasma and Energetic Atoms Electron Spectrometer (ELS), and topside radar sounding of the nightside ionosphere by the MEX Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS). In this event, EMM EMUS imaged a clear discrete aurora signature around moderately strong crustal magnetic fields on the nightside near the dusk terminator, 11 min before which MEX MARSIS measured a prominent local enhancement of the peak electron density in the nightside ionosphere and MEX ELS observed an in situ enhancement of suprathermal electrons at the corresponding location. A remarkable geographic agreement is found between the enhancements of the aurora, ionosphere, and suprathermal electrons, suggesting that the enhanced ionization and auroral emission are caused concurrently by precipitating suprathermal electrons. Subsequent images indicate that the discrete aurora slightly changed its shape in 15 min and mostly disappeared in a few hours. The MEX MARSIS measurements of the auroral ionosphere display overlapping ionospheric and surface echoes indicative of horizontal gradients of the peak electron density. Analysis of the overlapping echoes implies that the auroral ionosphere and electron precipitation could be highly structured with horizontal spatial scales on the order of several tens of km. MEX MARSIS also observed a non-auroral ionospheric enhancement with a wider spatial extent than the local auroral enhancement, suggesting alternative sources of the enhanced nightside ionosphere such as plasma transport. The comparison between the ionospheric structures measured by MEX MARSIS, suprathermal electron flux measured by MEX ELS, and discrete auroral emission imaged by EMM EMUS underscores the complexity of the auroral and non-auroral nightside ionospheres. This motivates further investigations of their sources, transport, and connections to the magnetotail dynamics of Mars.

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Magnetic Reconnection in the Martian Magnetotail: Occurrence Rate and Impact on Ion Loss

Cited by 4 publications

References 67 publications

Sinuous Aurora at Mars: A Link to the Tail Current Sheet?

Sinuous Aurora at Mars: A Link to the Tail Current Sheet?

Hall physics during magnetic reconnection with collision effect

Discrete aurora and the nightside ionosphere of Mars: an EMM–MEX conjunction of FUV imaging, ionospheric radar sounding, and suprathermal electron measurements

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