Radial Evolution of the Solar Wind Flow with Parker Solar Probe and Solar Orbiter

Abstract:

Parker Solar Probe and Solar Orbiter are providing unprecedented joint measurements of the radial evolution of the solar wind from below the Alfven point out to 1 au allowing new empirical constraints on its flow properties. We will show results from three recent and ongoing studies on this evolution: (1) We study the acceleration and heating of a stream from Parker to Solar Orbiter and find that “magnetic switchbacks” are necessary (and sufficient) to close the energy budget. (2) We examine the solar wind azimuthal flow measured over radial distances covered by Parker through the end of 2023 and assess the current prospects for measuring a signature of coronal corotation. Lastly (3), we explore how the measured radial evolution and Parker orbit can be used to infer large scale variation in the shape of the alfven critical surface, how it relates to coronal structure and how it has evolved over the solar cycle. We close with a brief look forward to the changing orbits in the remaining nominal missions and how they will further enable such studies.