Magnetosonic Mach number effect of the position of the bow shock at Mars in comparison to Venus

Edberg, Niklas J. T.; Lester, M.; Cowley, S. W. H.; Brain, D. A.; Fränz, M.; Barabash, S.

doi:10.1029/2009ja014998

Cited by 43 publications

(76 citation statements)

References 38 publications

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“…What is also interesting and unexpected is that the BS is at lower altitudes than normal during the interval preceding the high pressure pulse (24-25 February) even though the Mach number is generally low. Edberg et al (2009c) showed that the magnetosonic Mach number is an important factor for determining the altitude of the BS and the altitude decreases linearly with increasing Mach number.…”

Section: Discussionmentioning

confidence: 99%

Rosetta and Mars Express observations of the influence of high solar wind pressure on the Martian plasma environment

et al. 2009

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Abstract. We report on new simultaneous in-situ observations at Mars from Rosetta and Mars Express (MEX) on how the Martian plasma environment is affected by high pressure solar wind. A significant sharp increase in solar wind density, magnetic field strength and turbulence followed by a gradual increase in solar wind velocity is observed during ∼24 h in the combined data set from both spacecraft after Rosetta's closest approach to Mars on 25 February 2007. The bow shock and magnetic pileup boundary are coincidently observed by MEX to become asymmetric in their shapes. The fortunate orbit of MEX at this time allows a study of the inbound boundary crossings on one side of the planet and the outbound crossings on almost the opposite side, both very close to the terminator plane. The solar wind and interplanetary magnetic field (IMF) downstream of Mars are monitored through simultaneous measurements provided by Rosetta. Possible explanations for the asymmetries are discussed, such as crustal magnetic fields and IMF direction. In the same interval, during the high solar wind pressure pulse, MEX observations show an increased amount of escaping planetary ions from the polar region of Mars. We link the high pressure solar wind with the observed simultaneous ionCorrespondence to: N. J. T. Edberg (ne@irfu.se) outflow and discuss how the pressure pulse could also be associated with the observed boundary shape asymmetry.

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Section: Discussionmentioning

confidence: 99%

Rosetta and Mars Express observations of the influence of high solar wind pressure on the Martian plasma environment

et al. 2009

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“…7 The position of all BS (red dots) and MPB (green dots) crossings by MEX from 2004 until 2008. The red and green lines are previously obtained best fits to the boundaries derived from MGS measurements from Edberg et al (2008) EUV flux and solar cycle (Vignes et al 2000;Edberg et al 2009b), and the magnetosonic Mach number (Edberg et al 2010).…”

Section: Comparison Of Martian Imb and Bow Shock Sizes Shapes And Comentioning

confidence: 99%

The Induced Magnetospheres of Mars, Venus, and Titan

et al. 2011

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This article summarizes and aims at comparing the main features of the induced magnetospheres of Mars, Venus and Titan. All three objects form a well-defined induced magnetosphere (IM) and magnetotail as a consequence of the interaction of an external wind of plasma with the ionosphere and the exosphere of these objects. In all three, photoionization seems to be the most important ionization process. In all three, the IM displays a clear outer boundary characterized by an enhancement of magnetic field draping and massloading, along with a change in the plasma composition, a decrease in the plasma temperature, a deflection of the external flow, and, at least for Mars and Titan, an increase of the total density. Also, their magnetotail geometries follow the orientation of the upstream magnetic field and flow velocity under quasi-steady conditions. Exceptions to this are fossil fields observed at Titan and the near Mars regions where crustal fields dominate the magnetic topology. Magnetotails also concentrate the escaping plasma flux from these three objects and similar acceleration mechanisms are thought to be at work. In the case of Mars and Titan, global reconfiguration of the magnetic field topology (reconnection with the crustal sources and exits into Saturn's magnetosheath, respectively) may lead to important losses of C. Bertucci ( )

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“…The terminator bow shock lies further from the planet in the directions perpendicular to the IMF orientation (Zhang et al 1991a). The Martian bow shock flares and moves further from the planet as the solar wind Mach number decreases (Edberg et al 2010).…”

Section: Mars and Venusmentioning

confidence: 99%

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

et al. 2018

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Both heliophysics and planetary physics seek to understand the complex nature of the solar wind's interaction with solar system obstacles like Earth's magnetosphere, the ionospheres of Venus and Mars, and comets. Studies with this objective are frequently conducted with the help of single or multipoint in situ electromagnetic field and particle observations, guided by the predictions of both local and global numerical simulations, and placed in con- text by observations from far and extreme ultraviolet (FUV, EUV), hard X-ray, and energetic neutral atom imagers (ENA). Each proposed interaction mechanism (e.g., steady or transient magnetic reconnection, local or global magnetic reconnection, ion pick-up, or the KelvinHelmholtz instability) generates diagnostic plasma density structures. The significance of each mechanism to the overall interaction (as measured in terms of atmospheric/ionospheric loss at comets, Venus, and Mars or global magnetospheric/ionospheric convection at Earth) remains to be determined but can be evaluated on the basis of how often the density signatures that it generates are observed as a function of solar wind conditions. This paper reviews efforts to image the diagnostic plasma density structures in the soft (low energy, 0.1-2.0 keV) X-rays produced when high charge state solar wind ions exchange electrons with the exospheric neutrals surrounding solar system obstacles. The introduction notes that theory, local, and global simulations predict the characteristics of plasma boundaries such the bow shock and magnetopause (including location, density gradient, and motion) and regions such as the magnetosheath (including density and width) as a function of location, solar wind conditions, and the particular mechanism operating. In situ measurements confirm the existence of time-and spatial-dependent plasma density structures like the bow shock, magnetosheath, and magnetopause/ionopause at Venus, Mars, comets, and the Earth. However, in situ measurements rarely suffice to determine the global extent of these density structures or their global variation as a function of solar wind conditions, except in the form of empirical studies based on observations from many different times and solar wind conditions. Remote sensing observations provide global information about auroral ovals (FUV and hard X-ray), the terrestrial plasmasphere (EUV), and the terrestrial ring current (ENA). ENA instruments with low energy thresholds (∼ 1 keV) have recently been used to obtain important information concerning the magnetosheaths of Venus, Mars, and the Earth. Recent technological developments make these magnetosheaths valuable potential targets for high-cadence wide-field-of-view soft X-ray imagers.Section 2 describes proposed dayside interaction mechanisms, including reconnection, the Kelvin-Helmholtz instability, and other processes in greater detail with an emphasis on the plasma density structures that they generate. It focuses upon the questions that remain as yet unanswered, such as the significanc...

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Magnetosonic Mach number effect of the position of the bow shock at Mars in comparison to Venus

Cited by 43 publications

References 38 publications

Rosetta and Mars Express observations of the influence of high solar wind pressure on the Martian plasma environment

Rosetta and Mars Express observations of the influence of high solar wind pressure on the Martian plasma environment

The Induced Magnetospheres of Mars, Venus, and Titan

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

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