Mercury's magnetopause and bow shock from MESSENGER Magnetometer observations

Winslow, R. M.; Anderson, B. J.; Johnson, C. L.; Slavin, J. A.; Korth, H.; Purucker, Michael E.; Baker, D. N.; Solomon, Sean C.

doi:10.1002/jgra.50237

Cited by 195 publications

(481 citation statements)

References 67 publications

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“…The vertical gray bars identify time intervals when MESSENGER transited Mercury's magnetosheath and magnetosphere; the start and end times of each vertical gray bar mark the inbound and outbound crossings of MESSENGER through Mercury's bow shock (cf. Winslow et al 2013). The periods between the gray vertical bars in Figure 12 indicate that the spacecraft was immersed in the solar wind and are the intervals of interest here.…”

Section: The Sep Event At 040 Aumentioning

confidence: 99%

Longitudinal Properties of a Widespread Solar Energetic Particle Event on 2014 February 25: Evolution of the Associated Cme Shock

Lario

Kwon

Vourlidas

et al. 2016

ApJ

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We investigate the solar phenomena associated with the origin of the solar energetic particle (SEP) event observed on 2014 February 25 by a number of spacecraft distributed in the inner heliosphere over a broad range of heliolongitudes. These include spacecraft located near Earth; the twin Solar TErrestrial RElations Observatory spacecraft, STEREO-A and STEREO-B, located at ∼1 au from the Sun 153°west and 160°east of Earth, respectively; the MErcury Surface Space ENvironment GEochemistry and Ranging mission (at 0.40 au and 31°w est of Earth); and the Juno spacecraft (at 2.11 au and 48°east of Earth). Although the footpoints of the field lines nominally connecting the Sun with STEREO-A, STEREO-B and near-Earth spacecraft were quite distant from each other, an intense high-energy SEP event with Fe-rich prompt components was observed at these three locations. The extent of the extreme-ultraviolet wave associated with the solar eruption generating the SEP event was very limited in longitude. However, the white-light shock accompanying the associated coronal mass ejection extended over a broad range of longitudes. As the shock propagated into interplanetary space it extended over at least ∼190°i n longitude. The release of the SEPs observed at different longitudes occurred when the portion of the shock magnetically connected to each spacecraft was already at relatively high altitudes (2 R e above the solar surface). The expansion of the shock in the extended corona, as opposite to near the solar surface, determined the SEP injection and SEP intensity-time profiles at different longitudes.

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Section: The Sep Event At 040 Aumentioning

confidence: 99%

Longitudinal Properties of a Widespread Solar Energetic Particle Event on 2014 February 25: Evolution of the Associated Cme Shock

Lario

Kwon

Vourlidas

et al. 2016

ApJ

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“…Thus, there is no complete information about the solar wind plasma parameters, flow direction, and their variations, neither when MESSENGER is outside nor when it is inside Mercury's magnetosphere (e.g. Korth et al 2011;Baker et al 2013;Winslow et al 2013;Dewey et al 2015). These challenges also hold for the future ESA/JAXA mission to Mercury, BepiColombo (Benkhoff et al 2010), and its plasma packages including SERENA on Mercury Planetary Orbiter (MPO; Orsini et al 2010) and MPPE on Mercury Magnetospheric Orbiter (MMO; Saito et al 2010).…”

Section: <3mentioning

confidence: 99%

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

Fatemi

Poirier

Holmström

et al. 2018

A&A

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Aims. The lack of an upstream solar wind plasma monitor when a spacecraft is inside the highly dynamic magnetosphere of Mercury limits interpretations of observed magnetospheric phenomena and their correlations with upstream solar wind variations. Methods. We used AMITIS, a three-dimensional GPU-based hybrid model of plasma (particle ions and fluid electrons) to infer the solar wind dynamic pressure and Alfvén Mach number upstream of Mercury by comparing our simulation results with MESSENGER magnetic field observations inside the magnetosphere of Mercury. We selected a few orbits of MESSENGER that have been analysed and compared with hybrid simulations before. Then we ran a number of simulations for each orbit (∼30-50 runs) and examined the effects of the upstream solar wind plasma variations on the magnetic fields observed along the trajectory of MESSENGER to find the best agreement between our simulations and observations. Results. We show that, on average, the solar wind dynamic pressure for the selected orbits is slightly lower than the typical estimated dynamic pressure near the orbit of Mercury. However, we show that there is a good agreement between our hybrid simulation results and MESSENGER observations for our estimated solar wind parameters. We also compare the solar wind dynamic pressure inferred from our model with those predicted previously by the WSA-ENLIL model upstream of Mercury, and discuss the agreements and disagreements between the two model predictions. We show that the magnetosphere of Mercury is highly dynamic and controlled by the solar wind plasma and interplanetary magnetic field. In addition, in agreement with previous observations, our simulations show that there are quasi-trapped particles and a partial ring current-like structure in the nightside magnetosphere of Mercury, more evident during a northward interplanetary magnetic field (IMF). We also use our simulations to examine the correlation between the solar wind dynamic pressure and stand-off distance of the magnetopause and compare it with MESSENGER observations. We show that our model results are in good agreement with the response of the magnetopause to the solar wind dynamic pressure, even during extreme solar events. We also show that our model can be used as a virtual solar wind monitor near the orbit of Mercury and this has important implications for interpretation of observations by MESSENGER and the future ESA/JAXA mission to Mercury, BepiColombo.

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“…Using an average solar wind velocity of 430 km s −1 , this corresponds to a gyroradius of the interaction of about 37.5 km. Compared to global structures of the interaction, such as a subsolar magnetosheath thickness of about 1220 km (Winslow et al, 2013), a magnetohydrodynamic (MHD) approximation seems to be a valid approximation. The inverse gyrofrequency is about 0.5 s, which limits the time resolution for this approximation.…”

Section: Introductionmentioning

confidence: 99%

“…However, in contrast to the situation at Mercury, the interaction of the solar wind near the planet's surface is negligible at Earth. Due to the weak magnetic field at Mercury, the interaction region of the solar wind is much closer to the planet (Winslow et al, 2013). In particular, the subsolar bow shock distance to the center of the planet is on average about 1.89 R M at Mercury and 13 R E at Earth (R E = 6371 km).…”

Section: Introductionmentioning

confidence: 99%

Estimating a planetary magnetic field with time-dependent global MHD simulations using an adjoint approach

2017

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Abstract. The interaction of the solar wind with a planetary magnetic field causes electrical currents that modify the magnetic field distribution around the planet. We present an approach to estimating the planetary magnetic field from in situ spacecraft data using a magnetohydrodynamic (MHD) simulation approach. The method is developed with respect to the upcoming BepiColombo mission to planet Mercury aimed at determining the planet's magnetic field and its interior electrical conductivity distribution. In contrast to the widely used empirical models, global MHD simulations allow the calculation of the strongly time-dependent interaction process of the solar wind with the planet. As a first approach, we use a simple MHD simulation code that includes time-dependent solar wind and magnetic field parameters. The planetary parameters are estimated by minimizing the misfit of spacecraft data and simulation results with a gradient-based optimization. As the calculation of gradients with respect to many parameters is usually very time-consuming, we investigate the application of an adjoint MHD model. This adjoint MHD model is generated by an automatic differentiation tool to compute the gradients efficiently. The computational cost for determining the gradient with an adjoint approach is nearly independent of the number of parameters. Our method is validated by application to THEMIS (Time History of Events and Macroscale Interactions during Substorms) magnetosheath data to estimate Earth's dipole moment.

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Mercury's magnetopause and bow shock from MESSENGER Magnetometer observations

Cited by 195 publications

References 67 publications

Longitudinal Properties of a Widespread Solar Energetic Particle Event on 2014 February 25: Evolution of the Associated Cme Shock

Longitudinal Properties of a Widespread Solar Energetic Particle Event on 2014 February 25: Evolution of the Associated Cme Shock

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

Estimating a planetary magnetic field with time-dependent global MHD simulations using an adjoint approach

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