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The solar wind flows along the white lines, and atmospheric particles are lost to space along the red lines. The blue incomplete cone represents shock. Illustration: IRF Swedish Institute of Space Physics

Published: 18 September 2024

Publication by ISSI & ISSI-Beijing Team #582

Highlights

From the Teams

Publication

Mars

Solar Wind

Magnetosphere

Mars vs. solar wind

New Nature study by ISSI & ISSI-Beijing Team uncovers unexpected interaction between Mars and the solar wind.

New study from ISSI & ISSI-Beijing Team #582

The interaction between planets and stellar wind can lead to atmospheric loss and is therefore important for the evolution of planetary atmospheres. Planets in our solar system typically interact with solar wind traveling at a large angle to the embedded stellar magnetic field. For planets without an intrinsic magnetic field, this interaction creates an induced magnetosphere and a bow shock in front of the planet. However, when the angle between the solar wind velocity and the solar wind magnetic field (i.e., the cone angle) is small, the interaction is very different.

In this study, members of the ISSI team led by Wenya Li and André Galli, including PhD student and lead author Qi Zhang from IRF and Umeå University, show that when the cone angle is small at Mars, the induced magnetosphere degenerates. There is no shock on the dayside, only weak flank shocks. A cross-flow plume appears, and the ambipolar field drives planetary ions upstream.

Hybrid simulations of a four-degree cone angle case show agreement with observations from Mars Atmosphere and Volatile Evolution (MAVEN) and Mars Express (MEX). Degenerate induced magnetospheres are complex and not yet fully explored. Further studies are needed to understand the secondary effects on processes such as atmospheric loss through ion escape.

Read the study Access Press Release

Credits ESA/Webb, NASA & CSA, A. Martel