Speaker
Description
One of the first important observations made by NASA’s Parker Solar Probe spacecraft (launched 2018) is the omnipresence in the inner heliosphere of sudden deflections of the magnetic field, called switchbacks. The ubiquity of these large amplitude folds was a startling result, questioning our understanding of basic magnetized plasma dynamics. Not surprisingly, these structures have attracted considerable attention from the solar and heliospheric communities. Today there is broad consensus that switchbacks are Alfvénic structures and accompany the acceleration of the solar wind. Their appearance in patches suggests sources with distinct spatial/temporal organization in the low corona, plausibly tied to the supergranular network. Yet many key aspects remain unsettled. How often are switchbacks formed at the Sun—for example by interchange reconnection, coronal jets, or network-scale eruptions—and how often are they generated in situ through nonlinear wave evolution, turbulence, or velocity shear? What instabilities control their onset and morphology? How do they evolve as they propagate outward, and what is their net impact on the solar wind’s thermodynamics and angular-momentum budget? Because switchbacks are so common close to the Sun and leave clear imprints on particles and fields, they are expected to hold one of the keys to understanding solar-wind generation and acceleration.
In this paper I discuss the role of switchbacks in solar wind dynamics as well as their sources and evolution.
