Magnetic reconnection in the near‐Mars magnetotail: MAVEN observations

Harada, Yuki; Halekas, J. S.; McFadden, J. P.; Mitchell, David; Mazelle, C.; Connerney, J. E. P.; Espley, J. R.; Larson, D. E.; Brain, David; Andersson, L.; DiBraccio, G. A.; Collinson, G.; Livi, R.; Hara, Takuya; Ruhunusiri, S.; Jakosky, B. M.

doi:10.1002/2015gl065004

Cited by 68 publications

(105 citation statements)

References 47 publications

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“…The low indicates the dominant magnetic pres- sure as expected in the MPR (e.g., Ma et al, 2004). The heavier species display smaller V L changes (∼13 km/s for H + , ∼3 km/s for O + , and ∼2 km/s for O + 2 ions), suggesting that these ions are still unmagnetized and their motions are controlled mostly by electric fields, as is the case for reconnection events observed in the nightside magnetotail (Harada et al, 2015. The northward flow is opposite to southward flows nominally expected in the southern hemisphere (diverging plasma flows from the subsolar point toward the flank).…”

Section: Geophysical Research Lettersmentioning

confidence: 89%

Magnetic Reconnection on Dayside Crustal Magnetic Fields at Mars: MAVEN Observations

Harada

Halekas

DiBraccio

et al. 2018

Geophysical Research Letters

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The identification of magnetic reconnection on the dayside of Mars has been elusive owing to the lack of comprehensive plasma and field measurements. Here we present direct measurements of dayside in situ reconnection signatures by the comprehensive particles and fields package on board the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft over strong crustal magnetic fields in the southern hemisphere of Mars. During a crossing of a bifurcated current sheet consisting of northward and southward magnetic fields, MAVEN recorded (i) ionospheric photoelectrons trapped on closed magnetic field lines, (ii) Hall magnetic fields and a nonzero normal field with polarity consistent with a crossing northward of the X line, and (iii) northward Alfvénic ion jets. Dayside magnetic reconnection on crustal magnetic fields could control the global configuration and topology of the Martian magnetosphere and alter the ion escape pattern from the dayside ionosphere.

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Section: Geophysical Research Lettersmentioning

confidence: 89%

Magnetic Reconnection on Dayside Crustal Magnetic Fields at Mars: MAVEN Observations

Harada

Halekas

DiBraccio

et al. 2018

Geophysical Research Letters

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“…At Mars, observations of magnetic reconnection (Dubinin et al, 2008;Eastwood et al, 2008;Harada et al, 2015aHarada et al, , 2017, flux rope formation (DiBraccio et al, 2015;Eastwood et al, 2012;Hara et al, 2017), current sheet flapping , Marsward and tailward ion flows (Harada et al, 2015b), magnetic lobe dependence on IMF orientation Romanelli et al, 2015) and ionosphere magnetization , and bulk plasma escape (e.g., Brain et al, 2010;Halekas et al, 2016) have been reported in the magnetotail. At Mars, observations of magnetic reconnection (Dubinin et al, 2008;Eastwood et al, 2008;Harada et al, 2015aHarada et al, , 2017, flux rope formation (DiBraccio et al, 2015;Eastwood et al, 2012;Hara et al, 2017), current sheet flapping , Marsward and tailward ion flows (Harada et al, 2015b), magnetic lobe dependence on IMF orientation Romanelli et al, 2015) and ionosphere magnetization , and bulk plasma escape (e.g., Brain et al, 2010;Halekas et al, 2016) have been reported in the magnetotail.…”

Section: 1029/2018gl077251mentioning

confidence: 99%

The Twisted Configuration of the Martian Magnetotail: MAVEN Observations

DiBraccio

Luhmann

Curry

et al. 2018

Geophysical Research Letters

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Measurements provided by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft are analyzed to investigate the Martian magnetotail configuration as a function of interplanetary magnetic field (IMF) BY. We find that the magnetotail lobes exhibit a ~45° twist, either clockwise or counterclockwise from the ecliptic plane, up to a few Mars radii downstream. Moreover, the associated cross‐tail current sheet is rotated away from the expected location for a Venus‐like induced magnetotail based on nominal IMF draping. Data‐model comparisons using magnetohydrodynamic simulations are in good agreement with the observed tail twist. Model field line tracings indicate that a majority of the twisted tail lobes are composed of open field lines, surrounded by draped IMF. We infer that dayside magnetic reconnection between the crustal fields and draped IMF creates these open fields and may be responsible for the twisted tail configuration, similar to what is observed at Earth.

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“…A diversity of plasma characteristics in the Martian CS manifests in a wide range of estimated half‐thicknesses ( L ) from L ≤ 100 km (e.g., Halekas et al, ) to a few hundreds of kilometeres (e.g. Harada et al, , ). The comparison of the CS half‐thickness with particle thermal gyroradius and inertial length allowed Harada et al () to conclude that in a thin CS, protons and/or electrons carry the electric current, while in a thick CS, the role of quasi‐adiabatic heavy ions (O + ) becomes important.…”

Section: Introductionmentioning

confidence: 99%

Imprints of Quasi‐Adiabatic Ion Dynamics on the Current Sheet Structures Observed in the Martian Magnetotail by MAVEN

et al. 2017

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Numerous studies of the current sheets (CS) in the Earth's magnetotail showed that quasi‐adiabatic ion dynamics plays an important role in the formation of complicated multilayered current structures. In order to check whether the similar mechanisms operate in the Martian magnetotail, we analyzed 80 CS crossings using MAVEN measurements on the nightside of Mars at radial distances ~1.0–2.8RM. We found that CS structures experience similar dependence on the value of the normal component of the magnetic field at the neutral plane (BN) and on the ratio of the ion drift velocity outside the CS to the thermal velocity (VT/VD) as it was observed for the CSs in the Earth's magnetotail. For the small values of BN, a thin and intense CS embedded in a thicker one is observed. The half‐thickness L of this layer is ~30–100 km ≤ ρH+ (ρH+ is a gyroradius of thermal protons outside the CS). With the increase of BN, the L also increases up to several hundred kilometers (~ρO+, ρO2+), the current density decreases, and the embedding feature disappears. Our statistical analysis showed a good agreement between L values observed by MAVEN and the CS scaling obtained from the quasi‐adiabatic model, if the plasma characteristics in Martian CSs are used as input parameters. Thus, we may conclude that in spite of the differences in magnetic topology, ion composition, and plasma thermal characteristics observed in the Earth's and Martian magnetotails, similar quasi‐adiabatic mechanisms contribute to the formation of the CSs in the magnetotails of both planets.

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Magnetic reconnection in the near‐Mars magnetotail: MAVEN observations

Cited by 68 publications

References 47 publications

Magnetic Reconnection on Dayside Crustal Magnetic Fields at Mars: MAVEN Observations

Magnetic Reconnection on Dayside Crustal Magnetic Fields at Mars: MAVEN Observations

The Twisted Configuration of the Martian Magnetotail: MAVEN Observations

Imprints of Quasi‐Adiabatic Ion Dynamics on the Current Sheet Structures Observed in the Martian Magnetotail by MAVEN

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