MHD study of the planetary magnetospheric response during extreme solar wind conditions: Earth and exoplanet magnetospheres applications

Context. The stellar wind and the interplanetary magnetic field modify the topology of planetary magnetospheres. Consequently, the hazardous effect of the direct exposition to the stellar wind, for example, regarding the integrity of satellites orbiting the Earth or the habitability of exoplanets, depends upon the space weather conditions. Aims. The aim of the study is to analyze the response of an Earth-like magnetosphere for various space weather conditions and interplanetary coronal mass ejections. The magnetopause standoff distance, the open-close field line boundary, and plasma flows toward the planet surface are calculated. Methods. We used the magnetohydrodynamics code PLUTO in spherical coordinates to perform a parametric study of the dynamic pressure and temperature of the stellar wind as well as of the interplanetary magnetic field intensity and orientation. The range of the parameters we analyzed extends from regular to extreme space weather conditions, which is consistent with coronal mass ejections at the Earth orbit for the present and early periods of the solar main sequence. In addition, implications of sub-Afvenic solar wind configurations for the Earth and exoplanet magnetospheres were analyzed. Results. The direct precipitation of the solar wind at the Earth dayside in equatorial latitudes is extremely unlikely even during super coronal mass ejections. On the other hand, for early evolution phases during the solar main sequence, when the solar rotation rate was at least five times faster (<440 Myr), the Earth surface was directly exposed to the solar wind during coronal mass ejections. Today, satellites at high, geosynchronous, and medium orbits are directly exposed to the solar wind during coronal mass ejections because part of the orbit at the Earth dayside is beyond the nose of the bow shock.

Automated summary

This study analyzes the response of an Earth-like magnetosphere to different space weather conditions and interplanetary coronal mass ejections. The results show that direct precipitation of the solar wind at the Earth's dayside is unlikely even during super coronal mass ejections. However, during the early evolution phases of the solar main sequence, the Earth's surface was directly exposed to the solar wind during coronal mass ejections. Satellites in high, geosynchronous, and medium orbits are currently directly exposed to the solar wind during coronal mass ejections.