Summary

The heliosphere is an exceptional laboratory for plasma physics. Thanks to its accessibility through in situ measurements, we can directly test theories and develop models that are also fundamental to the study of other astrophysical environments. By exploring different regions of the heliosphere (solar wind, planetary magnetospheres, cometary environments), we can measure the electromagnetic fluctuations and distribution functions of the particles that make up the plasma, obtaining important information about the composition of the medium, its thermodynamic and energetic state, and the different modes that propagate through the system. The main themes to be addressed in the study of the heliosphere are (1) the existence of a hot solar corona giving rise to a supersonic plasma flow; (2) the evolution of the solar wind as it travels through interplanetary space; (3) the interaction of solar wind plasma with the various magnetized obstacles in the solar system (planetary and cometary magnetospheres).

Scientific justification

In this course, we propose to discuss some fundamental plasma physics processes, through theoretical reviews (morning lecture) and their illustration through practical work (afternoon) involving the analysis of in-situ data provided by various probes orbiting in heliospheric plasmas.
Among the processes covered:
– Expanding plasmas (solar wind, non-adiabatic expansion, etc.)
– Waves and turbulence
– Sun-planetary magnetosphere interaction
– Possible topics: plasma instabilities, shocks, magnetic reconnection (depending on a guest speaker from outside LIRA).
The course comprises theoretical lectures in the morning and practical work based on space data in the afternoon, to illustrate the practical applications of the topics introduced in the morning. This will also enable students to familiarize themselves with tools and techniques for analyzing in-situ measurements and testing them directly with satellite observations.

Preliminary program

Monday: Introduction to the physics of the Heliosphere, acceleration and expansion of the solar wind.
Practical work on solar wind measurements at several distances from the Sun, and comparison with classical models of plasma expansion (measurements from the Helios, Ulysses, Parker Solar Probe and Solar Orbiter missions).
Tuesday: Turbulence in space plasmas
Practical work on spectral analysis of time series in turbulent solar wind plasma (measurements from the Cluster and Parker Solar Probe missions).
Wednesday: Instrumentation and in-situ measurements
Practical work on the analysis of radio measurements (Solar Orbiter).
Thursday: Frontiers of Mercury’s magnetosphere: a planet under pressure. Practical work on analysis of data from the MESSENGER mission (via AMDA/CDPP) and comparison with MHD simulations.
Friday: Instabilities and/or discontinuities in plasmas (shocks, current layers, etc.): multi-instrument and multi-satellite vision (depending on available time).
Seminar by a specialist in place of practical work (possible topics: Instabilities, shocks, magnetic reconnection).