The last 60 years of space exploration have shown that the interplanetary medium is continually perturbed by a myriad of different solar winds and storms that transport solar material across the whole heliosphere. If there is a consensus on the source of the fast solar wind that is known to originate in coronal holes, the question is still largely debated on the origin of the slow solar wind (SSW). The abundance of heavy ions measured in situ provides a precious diagnostic of potential source regions, because the composition is established very low in the solar atmosphere at the interface between the dense chromosphere and the tenuous corona, and remains invariant during transport in the collisionless solar wind. The similar composition measured in situ in the SSW and spectroscopically in coronal loops suggests that a significant fraction of the SSW originates as plasma material that was initially trapped along corona loops and subsequently released in the solar wind. The recent observations from the Parker Solar Probe (PSP) mission also provide new insights on the nascent solar wind. A great challenge remains to explain both the composition and bulk properties of the SSW in a self-consistent manner. For this purpose we exploit and develop models with various degrees of complexity. This context constitutes the backbone of this thesis which is structured in four major steps: we begin by presenting a new technique that exploits white-light (WL) observations of the SSW taken from multiple vantage points to constrain global models of the solar atmosphere. We then exploit the first images taken by the Wide-Field Imager for Solar PRobe (WISPR) from inside the solar corona to test our global models at smaller scales because WISPR offers an unprecedented close-up view of the fine structure of streamers and of the nascent SSW. This work provides further evidence for the transient release of plasma trapped in coronal loops into the solar wind, that we interpret by exploiting high-resolution magneto-hydro-dynamics (MHD) simulations. Finally we develop and exploit a new multi-specie model of coronal loops called the Irap Solar Atmosphere Model (ISAM) to provide an in-depth analysis of the plasma transport mechanisms at play between the chromosphere and the corona. ISAM solves for the coupled transport of the main constituents of the solar wind with minor ions through a comprehensive treatment of collisions as well as partial ionization and radiative cooling/heating mechanisms near the top of the chromosphere. We use this model to study the different mechanisms that can preferentially extract ions according to their first-ionization-potential (FIP), from the chromosphere to the corona. In this process we compare the relative roles of frictional and thermal diffusive effects in enriching coronal loops with low-FIP elements that could be subsequently expelled in the SSW through the mechanisms discussed in the first part of this thesis.
Authors: Nicolas Poirier
Projects: None
Publication Status: Accepted & Published
Last Modified: 2022-09-12 11:51