Prof. Anna Tenerani, The University of Texas at Austin

"Alfvénic turbulence in the solar wind"

Abstract: The sun continuously emits a supersonic stream of plasma, constituted mainly by electrons and protons, known as the solar wind. The solar wind carries a broadband of fluctuations in velocity and magnetic fields that have been interpreted in terms of an ongoing turbulent cascade of so-called Alfvénic fluctuations. These fluctuations carry sufficient energy to explain the non-adiabatic temperature gradients in the wind as it expands in interplanetary space, and they may be a remnant of the flux responsible for coronal heating and solar wind acceleration close to the sun. However, a complete understanding of how Alfvénic fluctuations evolve in the expanding solar wind, and of how they interact with particles by heating the plasma, remains elusive. Parker Solar Probe (PSP), launched in 2018, is the first spacecraft to fly into the sun’s outer atmosphere, with the goal to understand what heats the corona and accelerates the solar wind. Here I will present some of the most interesting findings of PSP on Alfvénic turbulence and discuss longstanding as well as new open questions motivated by such observations.