A modelling approach to infer the solar wind dynamic pressure from magnetic field observations inside Mercury’s magnetosphere

Fatemi, Shahab; Poirier, Nicolas; Holmström, Mats; Lindkvist, Jesper; Wieser, Martin; Barabash, S.

doi:10.1051/0004-6361/201832764

Cited by 29 publications

(39 citation statements)

References 74 publications

(191 reference statements)

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“…The model self‐consistently couples the interior magnetic response to the ambient plasma environment using a semi‐implicit method (model details are extensively explained in Fatemi et al, ). Amitis has been previously used to study the plasma interaction with the Moon (Fatemi et al, ; Fuqua Haviland et al, ; Garrick‐Bethell et al, ; Poppe, ), asteroid 16 Psyche (Fatemi & Poppe, ), and Mercury (Fatemi et al, ) and our simulation results have been previously validated through comparison with analytical theories (Fuqua Haviland et al, ) and with ARTEMIS and MESSENGER observations (Fatemi et al, , ; Poppe, ).…”

Section: Modelmentioning

confidence: 68%

“…For both of these flybys, MESSENGER almost passed through the equatorial plane of Mercury where the IMF was planetward and northward during the M1 and planetward and southward during the M2 flyby (Slavin et al, , Slavin et al, ). As explained previously by Fatemi et al (), we used Amitis to infer solar wind plasma parameters upstream when MESSENGER is passing through the magnetosphere of Mercury during the M1 and M2 flybys. Our model (not shown here but explained in detail in Fatemi et al, ) suggests that the solar wind dynamic pressure during the M1 and M2 flybys was 7.0 and 8.7 nPa, respectively.…”

Section: Simulation Results and Comparison With Observationsmentioning

confidence: 99%

“…The MESSENGER spacecraft made the first (M1) and the second (M2) flybys of Mercury on 14 January 2008 and 6 October 2008, respectively, at similar true anomalies of ∼290° along Mercury's orbit (e.g., Slavin et al, , ; Solomon et al, ). As explained in detail in Fatemi et al (), we inferred the solar wind plasma dynamic pressure during those two flybys through comparison between our hybrid simulations and the magnetic field observation by MESSENGER. The parameters listed in Table for M1 and M2 flybys were obtained from the best match between our hybrid simulations and MESSENGER observations (also see section ).…”

Section: Modelmentioning

confidence: 99%

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Hybrid Simulations of Solar Wind Proton Precipitation to the Surface of Mercury

2020

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We examine the effects of the interplanetary magnetic field (IMF) orientation and solar wind dynamic pressure on the solar wind proton precipitation to the surface of Mercury using a hybrid-kinetic model. We use our model to explain observations of Mercury's neutral sodium exosphere and compare our results with MESSENGER observations. For the typical solar wind dynamic pressure at Mercury our model shows a high proton flux precipitates through the magnetospheric cusps to the high latitudes on both hemispheres on the dayside, centered near the noon meridian with ∼11 • latitudinal extent in the north and ∼21 • latitudinal extent in the south, which is consistent with MESSENGER observations. We show that this two-peak pattern is controlled by the radial component (B x ) of the IMF and not the B z . Our model suggests that the southward IMF and its associated magnetic reconnection do not play a major role in controlling plasma precipitation to the surface of Mercury through the cusps. We found that the total precipitation rate through both of the cusps remain constant and independent of the IMF orientation. We also show that the solar wind proton incidence rate to the entire surface of Mercury is higher when the IMF has a northward component and nearly half of the incidence flux impacts the low latitudes on the nightside. During extreme solar events (e.g., coronal mass ejections), our model suggests that over 70 nPa solar wind dynamic pressure is required for the entire surface of Mercury to be exposed to the solar wind plasma.

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Section: Modelmentioning

confidence: 68%

Section: Simulation Results and Comparison With Observationsmentioning

confidence: 99%

Section: Modelmentioning

confidence: 99%

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Hybrid Simulations of Solar Wind Proton Precipitation to the Surface of Mercury

2020

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“…Amitis employs the standard hybrid modeling technique by following individual ions according to particle‐in‐cell methods with electrons modeled as a charge‐neutralizing fluid. Amitis has been extensively tested against standard metrics as reported in Fatemi et al () and was recently used to investigate the interaction between the present‐day solar wind and, for example, the potentially magnetized asteroid 16 Psyche (Fatemi & Poppe, ) and Mercury (Fatemi et al, ). Here, the Moon is modeled as a purely resistive object that absorbs all particles that impact its surface; we neglect any possible effects from interior conductivity and associated induced fields (Dyal & Parkin, ; Fatemi et al, ; Sonett et al, ).…”

Section: Model Descriptionmentioning

confidence: 99%

The Lunar Paleo‐Magnetosphere: Implications for the Accumulation of Polar Volatile Deposits

Garrick‐Bethell

Poppe

Fatemi

2019

Geophysical Research Letters

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Analyses of lunar samples suggest the Moon once possessed a dynamo from ~4.25 Ga until perhaps as recently as 1 Ga, with surface field strengths between ~5 and 100 μT. While the exact timing, strength, and structure of these paleomagnetic fields are not precisely known, such relatively strong fields imply that the Moon also likely possessed a magnetosphere. Here, we present hybrid plasma simulations of the structure and morphology of the putative lunar “paleo‐magnetosphere” for varying surface field strengths and orientations, using ambient solar wind conditions representative of the early Sun. The presence of the paleo‐magnetosphere reduces total solar wind fluxes to the lunar surface overall yet, for a spin‐aligned dynamo, increases the relative solar wind flux to the lunar polar regions. In turn, the paleo‐magnetosphere may have altered the rate of volatile accretion to the Moon over its history.

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“…We further complement our analyses of MESSENGER HCM events with time-dependent global magnetosphere simulations, which have proven to be useful in interpreting and understanding in situ measurements at Mercury. A number of numerical models of different types have been applied to Mercury, such as global magnetohydrodynamic (MHD) models (e.g., Benna et al, 2010;Jia et al, 2015;Kabin et al, 2000Kabin et al, , 2008Kidder et al, 2008), hybrid models (e.g., Exner et al, 2018;Fatemi et al, 2018;Janhunen & Kallio, 2004;Müller et al, 2012;Trávníček et al, 2009Trávníček et al, , 2010Wang et al, 2010), and test particle simulations (e.g., Delcourt et al, 2002;Delcourt, 2013;Schriver et al, 2011;Seki et al, 2013). Of particular relevance to our investigation of the HCM events is the induction effect arising from Mercury's conducting core.…”

Section: Introductionmentioning

confidence: 99%

MESSENGER Observations and Global Simulations of Highly Compressed Magnetosphere Events at Mercury

et al. 2019

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We identify and examine all MErcury Surface Space ENvironment, GEochemistry, and Ranging (MESSENGER) crossings of Mercury's dayside magnetopause with magnetospheric field intensities ≥300 nT. The eight such events, which occurred under highly compressed magnetosphere conditions, are analyzed in the identical manner utilized by Slavin et al. (2014, https://doi.org/10.1002/2014JA020319). The results suggest that the eight highly compressed magnetosphere events represent the highest solar wind dynamic pressures for which the MESSENGER's orbit still passed below the magnetopause and provided measurements of the dayside magnetosphere. Using the magnetohydrodynamic model by Jia et al. (2015, https://doi.org/10.1002/2015JA021143) that electromagnetically couples Mercury's interior with its magnetosphere, a series of global simulations are conducted to quantitatively characterize the response of Mercury's magnetosphere to solar wind forcing. Combining the MESSENGER observations with the simulations, we have obtained a consistent picture of how Mercury's dayside magnetospheric configuration is controlled, separately and in combination, by induction‐driven shielding and reconnection‐driven erosion. For solar wind pressures of ∼40–90 nPa, compared with the average ∼10–15 nPa at Mercury's orbit, the shielding effects of induction in Mercury's core in standing‐off the solar wind typically exceed the erosion of the dayside magnetosphere due to reconnection for these events, most of which occurred under low magnetic shear conditions. For high magnetic shear across the magnetopause our simulation predicts that reconnection would dominate. Mercury's effective magnetic moment as inferred from magnetopause standoff distance ranges from 170 to 250 nT−RM3 for these events. These findings are of crucial importance for understanding the space weathering at Mercury and its contribution to the generation of Mercury's exosphere.

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A modelling approach to infer the solar wind dynamic pressure from magnetic field observations inside Mercury’s magnetosphere

Cited by 29 publications

References 74 publications

Hybrid Simulations of Solar Wind Proton Precipitation to the Surface of Mercury

Hybrid Simulations of Solar Wind Proton Precipitation to the Surface of Mercury

The Lunar Paleo‐Magnetosphere: Implications for the Accumulation of Polar Volatile Deposits

MESSENGER Observations and Global Simulations of Highly Compressed Magnetosphere Events at Mercury

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