Planetary Mach cones: Theory and observation

Slavin, J. A.; Holzer, Robert E.; Spreiter, J. R.; Stahara, S. S.

doi:10.1029/ja089ia05p02708

Cited by 78 publications

(71 citation statements)

References 31 publications

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“…These works concluded that the shock location depends on the solar cycle and solar EUV flux, the upstream solar wind parameters, and the orientation of the IMF (see also Phillips and McComas 1991 (Martinecz, et al 2008) Figure 5a shows Martinecz et al (2008) VEX BS and IMB fits and in Figure 5b a comparison with other shock models based on other data sets at solar minimum. The VEX BS fit is in good agreement with the model of Slavin et al (1984) based on Mariner 5,10 and Venera 4, 6, 9, 10 observations. During solar minimum, a comparison between the BS position and solar EUV flux (F50 index: 0.1 -50 nm integrated photons cm −2 s −1 and shifted to Venus) derived from SOHO SEM observations shows no apparent dependence (Martinecz et al 2008).…”

Section: Venussupporting

confidence: 68%

Effects of solar variability on planetary plasma environments and habitability

Bertucci

2011

Proc. IAU

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AbstractIntrinsic and induced planetary magnetospheres are the result of the transfer of energy and linear momentum between the solar wind and, respectively, the magnetic field and the atmospheres of solar system bodies. This transfer seems to be, however, more critical to the atmospheric evolution of unmagnetized objects such as Mars and Venus, as locally ionized planetary particles are accelerated by solar-wind induced electric fields, leading to atmospheric escape. The nature of the obstacle to the solar wind being different, intrinsic and induced magnetospheres respond differently to solar cycle changes in solar photon flux and solar wind properties. The influence of solar variability on planetary magnetospheres and its implications for atmospheric evolution based upon remote and in situ spacecraft measurements, and numerical simulations are discussed. In particular, the case of unmagnetized objects where non-thermal escape process might have played a role in their habitability conditions is considered.

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Section: Venussupporting

confidence: 68%

Effects of solar variability on planetary plasma environments and habitability

Bertucci

2011

Proc. IAU

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“…Similar differences between the planets are also seen in the ratio of proton inertia length to bow shock size, but the proton inertia length at Mars (few hundred km) is still very small compared to the Martian bow shock size (∼5000 km). The Mach numbers (Alfvén and Fast Magnetosonic) are similar among these three planets, varying only by a factor of ∼1.4 between Venus and Mars (Slavin et al, 1984).…”

Section: Introductionmentioning

confidence: 80%

“…A rough comparison of the solar wind plasma parameters (their ratios) among the regions near Venus, the Earth, and Mars is listed in Table 1, in which we adopt the Alfvén Mach number (M A ) from Slavin et al (1984) and a constant solar wind speed between Venus and Mars (Smith and Wolfe, 1979). The Venus-Earth difference in the bow shock size is due to the intrinsic dipole magnetic field that exists only at the Earth.…”

Section: Introductionmentioning

confidence: 99%

Comparison of accelerated ion populations observed upstream of the bow shocks at Venus and Mars

et al. 2011

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Abstract. Foreshock ions are compared between Venus andMars at energies of 0.6∼20 keV using the same ion instrument, the Ion Mass Analyser, on board both Venus Express and Mars Express. Venus Express often observes accelerated protons (2∼6 times the solar wind energy) that travel away from the Venus bow shock when the spacecraft location is magnetically connected to the bow shock. The observed ions have a large field-aligned velocity compared to the perpendicular velocity in the solar wind frame, and are similar to the field-aligned beams and intermediate gyrating component of the foreshock ions in the terrestrial upstream region. Mars Express does not observe similar foreshock ions as does Venus Express, indicating that the Martian foreshock does not possess the intermediate gyrating component in the upstream region on the dayside of the planet. Instead, two types of gyrating protons in the solar wind frame are observed very close to the Martian quasi-perpendicular bow shock within a proton gyroradius distance. The first type is observed only within the region which is about 400 km from the bow shock and flows tailward nearly along the bow shock with a similar velocity as the solar wind. The second type is observed up to about 700 km from the bow shock and has a bundled structure in the energy domain. A traversal on 12 July 2005, in which the energy-bunching came from bundling in the magnetic field direction, is further examined. The observed velocities of the latter population are consistent with multiple specular reflections of the solar wind at the bow shock, and the ions after the second reflection have a fieldaligned velocity larger than that of the de Hoffman-Teller velocity frame, i.e., their guiding center has moved toward inCorrespondence to: M. Yamauchi (m.yamauchi@irf.se) terplanetary space out from the bow shock. To account for the observed peculiarity of the Martian upstream region, finite gyroradius effects of the solar wind protons compared to the radius of the bow shock curvature and effects of cold ion abundance in the bow shock are discussed.

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“…incorrect asymptotic behavior unless distant crossings are included (Slavin et al, 1984), and do not consider specific heat ratio influence on the planetary bow shock position.…”

Section: Introductionmentioning

confidence: 99%

Wind observations of the terrestrial bow shock: 3-D shape and motion

et al. 2014

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Between late 1994 and early 2001 the Wind orbiter, generally targeted to stay in the solar wind, passed through the Earth's magnetosphere ∼50 times. About 450 distinct bow shock crossings were collected during the inbound and outbound bracketing each Wind perigee. These crossings and corresponding vectorial upstream solar wind measurements by the Wind MFI and SWE instruments are used to study the 3-D shape of the bow shock and its motion. Mapping of bow shock crossings to the Sun-Earth line and to the terminator plane is realized using a recent analytical model of the planetary bow shock. The asymmetry of the terrestrial bow shock in the terminator plane is studied as a function of Friedrichs diagram anisotropy. Analysis of the subsolar bow shock position as a function of Alfvenic Mach number M a during intervals of magnetic field aligned solar wind flow shows that the shock tends to approach the Earth when M a is decreasing, while for non field-aligned flows bow shock moves from the planet.

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Planetary Mach cones: Theory and observation

Cited by 78 publications

References 31 publications

Effects of solar variability on planetary plasma environments and habitability

Effects of solar variability on planetary plasma environments and habitability

Comparison of accelerated ion populations observed upstream of the bow shocks at Venus and Mars

Wind observations of the terrestrial bow shock: 3-D shape and motion

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