scholarly journals Statistical analysis of the location of the Martian magnetic pileup boundary and bow shock and the influence of crustal magnetic fields

2008 ◽  
Vol 113 (A8) ◽  
pp. n/a-n/a ◽  
Author(s):  
N. J. T. Edberg ◽  
M. Lester ◽  
S. W. H. Cowley ◽  
A. I. Eriksson
Keyword(s):  
Statistical Analysis ◽  
Magnetic Fields ◽  
Bow Shock ◽  
Magnetic Pileup Boundary

scholarly journals On the alignment of velocity and magnetic fields within magnetosheath jets

2020 ◽  
Vol 38 (2) ◽  
pp. 287-296
Author(s):  
Ferdinand Plaschke ◽  
Maria Jernej ◽  
Heli Hietala ◽  
Laura Vuorinen
Keyword(s):  
Magnetic Fields ◽  
Entire Range ◽  
Dynamic Pressure ◽  
Bow Shock ◽  
Superposed Epoch Analysis ◽  
Magnetospheric Multiscale ◽  
Study Results ◽  
Epoch Analysis ◽  
The Magnetic Field

Abstract. Jets in the subsolar magnetosheath are localized enhancements in dynamic pressure that are able to propagate all the way from the bow shock to the magnetopause. Due to their excess velocity with respect to their environment, they push slower ambient plasma out of their way, creating a vortical plasma motion in and around them. Simulations and case study results suggest that jets also modify the magnetic field in the magnetosheath on their passage, aligning it more with their velocity. Based on Magnetospheric Multiscale (MMS) jet observations and corresponding superposed epoch analyses of the angles ϕ between the velocity and magnetic fields, we can confirm that this suggestion is correct. However, while the alignment is more significant for faster than for slower jets, and for jets observed close to the bow shock, the overall effect is small: typically, reductions in ϕ of around 10∘ are observed at jet core regions, where the jets' velocities are largest. Furthermore, time series of ϕ pertaining to individual jets significantly deviate from the superposed epoch analysis results. They usually exhibit large variations over the entire range of ϕ: 0 to 90∘. This variability is commonly somewhat larger within jets than outside them, masking the systematic decrease in ϕ at core regions of individual jets.

scholarly journals Magnetic clouds' structure in the magnetosheath as observed by Cluster and Geotail: four case studies

2014 ◽  
Vol 32 (10) ◽  
pp. 1247-1261 ◽  
Author(s):  
L. Turc ◽  
D. Fontaine ◽  
P. Savoini ◽  
E. K. J. Kilpua
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Fields ◽  
Bow Shock ◽  
Field Direction ◽  
Magnetic Clouds ◽  
Magnetic Field Direction ◽  
Field Orientation ◽  
The Impact ◽  
The Magnetic Field

Abstract. Magnetic clouds (MCs) are large-scale magnetic flux ropes ejected from the Sun into the interplanetary space. They play a central role in solar–terrestrial relations as they can efficiently drive magnetic activity in the near-Earth environment. Their impact on the Earth's magnetosphere is often attributed to the presence of southward magnetic fields inside the MC, as observed in the upstream solar wind. However, when they arrive in the vicinity of the Earth, MCs first encounter the bow shock, which is expected to modify their properties, including their magnetic field strength and direction. If these changes are significant, they can in turn affect the interaction of the MC with the magnetosphere. In this paper, we use data from the Cluster and Geotail spacecraft inside the magnetosheath and from the Advanced Composition Explorer (ACE) upstream of the Earth's environment to investigate the impact of the bow shock's crossing on the magnetic structure of MCs. Through four example MCs, we show that the evolution of the MC's structure from the solar wind to the magnetosheath differs largely from one event to another. The smooth rotation of the MC can either be preserved inside the magnetosheath, be modified, i.e. the magnetic field still rotates slowly but at different angles, or even disappear. The alteration of the magnetic field orientation across the bow shock can vary with time during the MC's passage and with the location inside the magnetosheath. We examine the conditions encountered at the bow shock from direct observations, when Cluster or Geotail cross it, or indirectly by applying a magnetosheath model. We obtain a good agreement between the observed and modelled magnetic field direction and shock configuration, which varies from quasi-perpendicular to quasi-parallel in our study. We find that the variations in the angle between the magnetic fields in the solar wind and in the magnetosheath are anti-correlated with the variations in the shock obliquity. When the shock is in a quasi-parallel regime, the magnetic field direction varies significantly from the solar wind to the magnetosheath. In such cases, the magnetic field reaching the magnetopause cannot be approximated by the upstream magnetic field. Therefore, it is important to take into account the conditions at the bow shock when estimating the impact of an MC with the Earth's environment because these conditions are crucial in determining the magnetosheath magnetic field, which then interacts with the magnetosphere.

scholarly journals Statistical analysis of the interplay between interstellar magnetic fields and filaments hostingPlanckGalactic cold clumps

2019 ◽  
Vol 485 (2) ◽  
pp. 2825-2843 ◽  
Author(s):  
D Alina ◽  
I Ristorcelli ◽  
L Montier ◽  
E Abdikamalov ◽  
M Juvela ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Magnetic Fields

Statistical analysis of diffuse ion events upstream of the Earth's bow shock

1994 ◽  
Vol 99 (A7) ◽  
pp. 13389 ◽  
Author(s):  
K. J. Trattner ◽  
E. Möbius ◽  
M. Scholer ◽  
B. Klecker ◽  
M. Hilchenbach ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Bow Shock ◽  
Earth’S Bow Shock

scholarly journals Characteristics of <u>></u> 290 keV magnetosheath ions

1999 ◽  
Vol 17 (5) ◽  
pp. 650-658 ◽  
Author(s):  
I. Karanikola ◽  
G. C. Anagnostopoulos ◽  
A. Rigas
Keyword(s):  
Statistical Analysis ◽  
Shock Waves ◽  
Space Plasma ◽  
High Energy ◽  
Bow Shock ◽  
Occurrence Frequency ◽  
Space Plasma Physics ◽  
Energetic Ions ◽  
Time Periods ◽  
Statistical Results

Abstract. We performed a statistical analysis of 290-500 keV ion data obtained by IMP-8 during the years 1982-1988 within the earth's magnetosheath and analysed in detail some time periods withdistinct ion bursts. These studies reveal the following characteristics for magnetosheath 290-500 keV energetic ions: (a) the occurrence frequency and the flux of ions increase with increasing geomagnetic activity as indicated by the Kp index; the occurrence frequency was found to be as high as P > 42% for Kp > 2, (b) the occurrence frequency in the dusk magnetosheath was found to be slightly dependent on the local time and ranged between ~30% and ~46% for all Kp values; the highest occurrence frequency was detected near the dusk magnetopause (21 LT), (c) the high energy ion bursts display a dawn-dusk asymmetry in their maximum fluxes, with higher fluxes appearing in the dusk magnetosheath, and (d) the observations in the dusk magnetosheath suggest that there exist intensity gradients of energetic ions from the bow shock toward the magnetopause. The statistical results are consistent with the concept that leakage of magnetospheric ions from the dusk magnetopause is a semi-permanent physical process often providing the magnetosheath with high energy (290-500 keV) ions.Key words. Magnetospheric physics (magnetosheath; planetary magnetospheres). Space plasma physics (shock waves).

scholarly journals Probing Bow Shocks Around Exoplanets During Transits

2011 ◽  
Vol 7 (S282) ◽  
pp. 117-118
Author(s):  
A. A. Vidotto ◽  
M. Jardine ◽  
C. Helling
Keyword(s):  
Magnetic Fields ◽  
Giant Planet ◽  
Bow Shock ◽  
Light Curves ◽  
Planetary Orbit ◽  
Stellar Radiation ◽  
Planetary Magnetic Fields ◽  
Bow Shocks ◽  
Gas Giant ◽  
Shock Detection

AbstractHere, we summarise the conditions that might lead to the formation of a bow shock surrounding a planet's magnetosphere. Such shocks are formed as a result of the interaction of a planet with its host star wind. In the case of close-in planets, the shock develops ahead of the planetary orbit. If this shocked material is able to absorb stellar radiation, the shock signature can be revealed in (asymmetric) transit light curves. We propose that this is the case of the gas giant planet WASP-12b, whose near-UV transit observations have detected the presence of an extended material ahead of the planetary orbit. We show that shock detection through transit observations can be a useful tool to constrain planetary magnetic fields.

Modification of the magnetosheath due to the high-speed jets propagation.

2020 ◽  
Author(s):  
Oleksandr Goncharov ◽  
Herbert Gunell ◽  
Maria Hamrin ◽  
Linus Norenius ◽  
Olga Gutynska
Keyword(s):  
Statistical Analysis ◽  
Velocity Component ◽  
High Speed ◽  
Dynamic Pressure ◽  
Cone Angle ◽  
Bow Shock ◽  
The Earth ◽  
Magnetospheric Multiscale ◽  
Wide Range ◽  
Statistical Studies

&lt;p&gt;Plasmoids, defined as plasma entities with a higher anti-sunward velocity component than the surrounding plasma, have been observed in the magnetosheath in recent years. Among other denominations, plasmoids are also called &amp;#8220;magnetosheath jets&amp;#8221; and can be classified by transient localized enhancements in dynamic pressure. Propagating through the magnetosheath, jets do not only affect the magnetopause and magnetosphere. Jets pushed slower ambient magnetosheath plasma out of their way. As a result, plasma moves around the jets, and it is slowed down or could even be pushed in the sunward direction. Consequently, jets may create anomalous flows and be a source of additional turbulence. Using the magnetosheath measurements by the Magnetospheric Multiscale (MMS) and THEMIS spacecraft, and comparing several criteria, we have identified several thousand events in the wide range of bow shock distances. Previous statistical studies have shown that jet occurrence is almost exclusively controlled by the angle between the IMF and the Earth&amp;#8211;Sun line (cone angle), and jets are predominantly observed when this cone angle is small. However, high-speed jets downstream of the quasi-perpendicular bow shock are very common. Our statistical analysis shows differences of jets evolution in the quasi-parallel and quasi-perpendicular magnetosheath regions. We discuss their properties, nature and relation to anomalies regions in the magnetosheath.&lt;/p&gt;

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