In Situ Categorization and Coronal Origins of Different Slow Solar Wind Types

Slow solar wind is known to be much more variable, in terms of plasma parameters, turbulence characteristics and speed, than the fast solar wind thought to emanate principally from coronal holes. While the topology of the coronal field is fairly simply understood, the source regions for the slow wind also remain more mysterious and dependent on the phase of the solar cycle. Active regions, boundaries of coronal holes or small coronal hole extensions may all be part of this, together with pseudostreamers and the pseudostreamer belt, related but not identical to the S-web concept. Within the slow wind, a number of periods have been identified where the turbulence is essentially Alfvénic (Marsch et al. 1981, D'Amicis and Bruno, 2015). Other indicators also seem to find that this slow wind is really slow "fast" wind. Is the difference between this Alfvénic slow wind and the standard slow wind associated with the origin, or is the coronal topology at the source completely different as initial indications seem to show? How do turbulence characteristics explored in detail compare to the other slow wind plasma (composition, distribution function) characteristics? These are the questions we attempt to respond to, also in anticipation of the exploration of the inner heliosphere soon to be carried out by Parker Solar Probe and Solar Orbiter.