Journal article
The Structure of the Martian Quasi‐Perpendicular Supercritical Shock as Seen by MAVEN
Journal of geophysical research. Space physics, Vol.126(9), e2020JA028938
09/2021
DOI: 10.1029/2020JA028938
Abstract
The Martian bow shock is a rich example of a supercritical, mass‐loaded collisionless shock that coexists with ultra‐low frequency upstream waves that are generated by the pick‐up of exospheric ions. The small size of the bow shock stand‐off distance (comparable with the solar wind ion convective gyroradius) raises questions about the nature of the particle acceleration and energy dissipation mechanism at work. The study of the Martian shock structure is crucial to understand its microphysics and is of special interest to understand the solar wind—planet interaction with a virtually unmagnetized body. We report on a complete identification and first characterization of the supercritical substructures of the Martian quasi‐perpendicular shock, under the assumption of a moving shock layer, using MAVEN magnetic field and solar wind plasma observations for two examples of shock crossings. We obtained substructures length‐scales comparable to those of the Terrestrial shock, with a narrow shock ramp of the order of a few electron inertial lengths. We also observed a well defined foot (smaller than the proton convected gyroradius) and overshoot that confirm the importance of ion dynamics for dissipative effects.
Plain Language Summary
The supermagnetosonic solar wind interacts with the Martian plasma environment and a shock wave is formed that decelerates, heats up and compresses the flow. Depending on the orientation of the interplanetary magnetic field and the strength of the incident solar wind flow, there are different mechanisms responsible for the dissipation that transforms the solar wind kinetic energy into heat. To understand these mechanisms, it is crucial to study the shock structure. In this study, we analyze the structure of the Martian supercritical quasi‐perpendicular shock using MAVEN measurements, and find consistent results with the Terrestrial bow shock, despite the differences between the way each planet interacts with the solar wind.
Key Points
A new methodology to identify the supercritical quasi‐perpendicular shock substructures is applied to the Martian bow shock
All three supercritical substructures are identified and their thickness is derived for the first time using an estimated shock speed
The reported ramp width is comparable with the electron inertial length, which is compatible with Earth observations
Details
- Title: Subtitle
- The Structure of the Martian Quasi‐Perpendicular Supercritical Shock as Seen by MAVEN
- Creators
- S. Burne - Institute of Astronomy and Space PhysicsC. Bertucci - Institute of Astronomy and Space PhysicsC. Mazelle - Research Institute in Astrophysics and PlanetologyL. F. Morales - Institute of Astronomy and Space PhysicsK. Meziane - University of New BrunswickJ. Halekas - University of IowaC. M. Fowler - Berkeley CollegeJ. Espley - Goddard Space Flight CenterD. Mitchell - Berkeley CollegeE. Penou - Research Institute in Astrophysics and Planetology
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.126(9), e2020JA028938
- DOI
- 10.1029/2020JA028938
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Number of pages
- 23
- Grant note
- Agencia de Promoción Científica y Tecnológica (Argentina) (PICT 1707‐2015 and 1103‐2018) CNES
- Language
- English
- Date published
- 09/2021
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984428837302771
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