Plans d'accès
Webmail
Accueil > A propos du LPP > Communication > Actualités archivées > 2023 > Ripples at the surface of the terrestrial bow-shock when the solar wind blows at high Mach numbers
Ripples at the surface of the terrestrial bow-shock when the solar wind blows at high Mach numbers
Toutes les versions de cet article : [English] [français]
The Sun continuously emits charged particles, mainly protons and electrons, flowing out at supermagnetosonic speed : this is the solar wind. Because of its high speed, its interaction with the terrestrial magnetic field generates a shock wave, traditionally called bow-shock, standing in front of the planet. Shaped as a gigantic paraboloid umbrella, the bow-shock plays the important role of shielding Earth’s environment from the direct penetration of solar energetic particles by diverting them away from it.
In a recent paper in Journal of Atmospheric and Solar-Terrestrial Physics, E. Cazzola, in post-doc in the space plasma team at LPP and his collaborators have simulated the bow-shock in steady conditions taking into account the presence of an interplanetary magnetic field perpendicular to the direction of the Sun, as well as perpendicular to the incident solar wind. While the bow-shock surface is smooth for slow solar winds, E. Cazzola et al. have observed that ripples appear at its surface for large solar wind speeds. These ripples are elongated in the direction perpendicular to the interplanetary magnetic field and propagate from the nose of the bow shock towards the flanks as shown in the figure.
Different processes can be responsible for the generation and propagation of waves at small or large scales et the shock surface. Thanks to the 3D hybrid formalism here adopted (the ions are treated as individual particles, the electrons as a fluid), E. Cazzola et al. have suggested that they could be generated by a mechanism based on the ions dynamics, called shock reformation. Briefly, the bow-shock forms a barrier reflecting part of the incident flow. The direction of the interplanetary magnetic field, tangent to the surface at the nose, contributes to efficiently accumulate reflected particles upstream the shock front. A new shock front thus starts to grow ahead the previous one, prior to being pushed back by the flow to the initial equilibrium position. This cyclic back and forth motion of the bow-shock surface near its nose initiates a surface wave which then propagates away from the nose along the bow-shock’s flanks.
Further details can be found in :
Cazzola, E., Fontaine, D., & Savoini, P. (2023). On the 3D global dynamics of terrestrial bow-shock rippling in a quasi-perpendicular interaction with steady solar wind. Journal of Atmospheric and Solar-Terrestrial Physics, 246, 106053,
https://doi.org/10.1016/j.jastp.2023.106053.
Contacts at LPP : Emanuele Cazzola, Dominique Fontaine and Philippe Savoini, « space plasmas » team
Dans la même rubrique :
- 1ère Journée scientifique HelioSwarm France (LPP, 5 mai 2023, Paris)
- Le champ magnétique solaire vu en stéréo
- Le LPP au congrès général des 150 ans de la Société Française de Physique
- Ondulations à la surface du choc terrestre lorsque le vent solaire souffle à forts nombres de Mach
- Journée à la mémoire de Nicole Cornilleau le 25 septembre
- Vincent David a soutenu sa thèse "Multiscale solar wind turbulence : from theory to observations"
- Pauline Simon a soutenu sa thèse "D’une pression isotrope à l’anisotropie de pression dans les plasmas spatiaux turbulents : Investigation analytique, numérique et observationnelle"
- Collaboration interdisciplinaire autour de la turbulence d’ondes
- BepiColombo/Mio détecte les premières ondes électromagnétiques haute fréquence dans l’environnement plasma de Mercure
- Nomination de Catherine Krafft comme Membre Sénior de l’Institut Universitaire de France (IUF)
- Fête de la Science 2023
- Des chercheurs du LPP ont participé à deux ouvrages pour mieux faire connaître la physique
- Pierre Morel a soutenu son HDR « Contribution à l’étude des instabilités, de la turbulence, et du transport, dans les plasmas magnétisés »
- COMHET : une nouvelle étape dans la collaboration LPP/SAFRAN sur les propulseurs électriques
- Jean-Paul Booth reçoit le prix Nishizawa 2023
- Chen Xing a soutenu sa thèse sur le rôle de la reconnexion magnétique dans l’évolution des tubes de flux magnétique des éruptions solaires
- Sae Aizawa a été recrutée comme chargée de recherche CNRS au LPP
- Tarek Ben Slimane a soutenu sa thèse "Investigation of the Optical Emission of Hall Effect Thrusters using Collisional Radiative Models, PIC Simulations, and Machine Learning"
- Hang Yang a soutenu sa thèse "Multi-periodic and random mode of Atmospheric Pressure Plasma Jets and their interactions with liquid and biological targets"
- Edmond Baratte a soutenu sa thèse "An experimental and numerical investigation of fundamental mechanisms in CO2-CH4 plasmas"
