Analysis of the new solar wind observations for space weather modeling

Details

Supervisors

Pierrard, Viviane

Faculty

Faculté des sciences

Degree label

Master [120] en sciences physiques, à finalité approfondie

Abstract

The solar wind, the continuous outflow of material from the solar surface, is mainly composed of protons and electrons that are accelerated throughout the heliosphere up to a few hundred km/s. Although many theoretical models have been developed since the first solar wind observations in the sixties, we still do not completely comprehend the mechanism behind the acceleration of the solar wind. Understanding the acceleration of the solar wind is critical in space weather since an accurate description of the solar wind velocity is required in order to forecast the exact trajectory of Coronal Mass Ejection (CME) which generates geomagnetic storms on Earth. Parker Solar Probe (PSP) and Solar Orbiter (SolO) are both currently orbiting the Sun and providing new insights into the acceleration of the solar wind. In this work, the PSP data measured up to a distance of 13.3 solar radii (Rs) is used to reveal the presence of correlations’ evolution with radial distance of solar wind macroscopic quantities. Then an improved kinetic exospheric model is constrained on PSP, SolO and Omni data and compared with the correlations found by PSP. This model includes suprathermal electrons to explain the acceleration of the solar wind. Finally, a detailed study of the Velocity Distribution Functions (VDF) produced by the model is provided by comparing with the observed VDF from PSP at 17.2 Rs. It showed that the kinetic exospheric model is able to explain part of the acceleration of the solar wind and that future improvements could be made on the modeled proton VDF.