A Comparative Study of Magnetic Flux Ropes in the Nightside Induced Magnetosphere of Mars and Venus

Hara, Takuya; Huang, Zesen; Mitchell, David; DiBraccio, G. A.; Brain, David; Harada, Yuki; Luhmann, J. G.

doi:10.1029/2021ja029867

Cited by 5 publications

(6 citation statements)

References 64 publications

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“…In addition, we have to remind the readers that our results reveal the average morphology of the tail current sheet. Given the large variability of the cross-tail current sheet location in MSE coordinates (e.g., twisted effect), the averaged characteristics of individual tail current sheets might be different to our results (e.g., DiBraccio et al, 2018;Hara et al, 2022;Harada et al, 2017).…”

Section: Average Structure Of the Magnetotail Current Sheetcontrasting

confidence: 87%

“…Recent studies have demonstrated that the crustal fields could complicate the structure of Martian magnetotail (DiBraccio et al, 2018(DiBraccio et al, , 2022Hara et al, 2022;Luhmann et al, 2015;Xu et al, 2020). The open field lines generated by the reconnection between IMF and crustal fields will overlap with the induced field lines, leading to the twist tail.…”

Section: Discussionmentioning

confidence: 99%

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Three‐Dimensional Configuration of Induced Magnetic Fields Around Mars

et al. 2022

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Using over 6 years of magnetic field data (October 2014–December 2020) collected by the Mars Atmosphere and Volatile EvolutioN, we conduct a statistical study on the three‐dimensional average magnetic field structure around Mars. We find that this magnetic field structure conforms to the pattern typical of an induced magnetosphere, that is, the interplanetary magnetic field (IMF) which is carried by the solar wind and which drapes, piles up, slips around the planet, and eventually forms a tail in the wake. The draped field lines from both hemispheres along the direction of the solar wind electric field (E) are directed toward the nightside magnetic equatorial plane, indicating that they are “sinking” toward the wake. These “sinking” field lines from the +E‐hemisphere (E pointing away from the plane) are more flared and dominant in the tail, while the field lines from the –E‐hemisphere (E pointing toward) are more stretched and “pinched” toward the plasma sheet. Such highly “pinched” field lines even form a loop over the pole of the –E‐hemisphere. The tail current sheet also shows an E‐asymmetry: the sheet is thicker with a stronger tailward trueJ→×trueB→ $\overrightarrow{J}\times \overrightarrow{B}$ force at +E‐flank, but much thinner and with a weaker trueJ→×trueB→ $\overrightarrow{J}\times \overrightarrow{B}$ (even turns sunward) at –E‐flank. Additionally, we find that IMF Bx can induce a kink‐like field structure at the boundary layer; the field strength is globally enhanced and the field lines flare less during high dynamic pressure.

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Section: Average Structure Of the Magnetotail Current Sheetcontrasting

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Three‐Dimensional Configuration of Induced Magnetic Fields Around Mars

et al. 2022

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“…The quasi-perpendicularity between the axis and M CS , as well as the opposite helicities of the flux ropes on either side of the current sheet, suggest they may be generated by dayside ionospheric instabilities and dragged into the tail by the solar wind. The criterion and result are consistent with previous research (e.g., Hara et al, 2022Hara et al, , 2017bLuhmann & Cravens, 1991).…”

Section: Flux Ropes On the Edge Of The Current Sheetsupporting

confidence: 92%

“…The magnetic observation signature of a flux rope is susceptible to its orientation, as well as the spacecraft trajectory through the flux rope. The LMN coordinates obtained from the minimum variance analysis (MVA) (Sonnerup & Scheible, 1998) has been proven to be advantageous in determining the orientation and structure (e.g., Bowers et al., 2021; Briggs et al., 2011; Hara et al., 2022; Sibeck et al., 1984; Vignes et al., 2004). The L, M, and N represent the maximum, intermediate, and minimum variance direction, and their corresponding eigenvalues are λ L , λ M, and λ N , respectively.…”

Section: Methodsmentioning

confidence: 99%

Heavy Ion Escape From Martian Wake Enhanced by Magnetic Reconnection

Wang

Huang

et al. 2022

JGR Planets

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Mars is a dry planet with a history of a warm and wet environment. Hydrogen and oxygen continuously escape from the unmagnetized planet. Although the heavy ion escape rate in the wake region is low due to Mars' obstruction, there are reports of events with bursty and enhanced ion escape. Here, we first find the evidence of the Alfvenic dayside‐produced plasma clouds accelerated by magnetic reconnection, which provides an explanation for the wake bursty mass escape by the observations from the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. In the event reported by this study, two types of flux ropes were successively observed in the magnetic reconnection exhaust in the Martian wake. One is generated by the reconnection, while others are produced by dayside boundary instability. The ions convected from the dayside, as well as the local original ions, can both be accelerated to be Alfvenic and expelled in the Martian tail by reconnection. The oxygen escape rate in the reconnection exhaust is estimated to be a quarter of the previous statistical result in the entire wake region.

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“…Sinuous aurora also depends strongly on IMF clock angle, with occurrence twice as likely for northnortheast and south-southwest clock angles. Sinuous aurora orientation shows a complex dependence on clock angle whereby sinuous aurora are approximately aligned with the solar wind convection electric field (E conv ) direction, albeit with significant scatter and moderate counterclockwise and clockwise twists in MSE coordinates for eastward and westward IMF conditions, respectively, similar to twists observed in the magnetotail current sheet by Hara et al (2022). Lastly, sinuous aurora appear almost exclusively in the hemisphere to which E conv points.…”

Section: Discussionmentioning

confidence: 82%

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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A Comparative Study of Magnetic Flux Ropes in the Nightside Induced Magnetosphere of Mars and Venus

Cited by 5 publications

References 64 publications

Three‐Dimensional Configuration of Induced Magnetic Fields Around Mars

Three‐Dimensional Configuration of Induced Magnetic Fields Around Mars

Heavy Ion Escape From Martian Wake Enhanced by Magnetic Reconnection

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

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