Alfvénic Slow Solar Wind: characteristics and origin
Abstract
The solar wind is a turbulent medium whose behavior is mostly determined by the nonlinear interaction between inward and outward propagating Alfvén waves. The purest examples of Alfvénic fluctuations are found in the trailing edges of fast solar wind streams. The slow wind usually has a lower degree of Alfvénicity being more strongly intermixed with structures of non-Alfvénic nature. However, as already found in the past, our recent analysis shows that under certain circumstances, even slow wind can be highly Alfvénic with fluctuations sometimes as wide as that of the fast wind. In this study we explore many facets of the Alfvénic slow solar wind spanning from the study of the source regions and their connection to coronal structures, to the micro-physics of distribution functions, anisotropies, to the role of turbulence and wave-particle interactions in solar wind heating, which are among the main topics of this session. It has been found that the Alfvénic slow wind is more similar to the fast wind rather than to the typical slow wind suggesting a similar origin for the two types of solar wind. Actually the Alfvénic slow wind does not originate from active regions or the cusp of the helmet streamers as the typical slow wind rather from the boundary between streamers and coronal holes. This would determine the similarities with the fast solar wind suggesting a major role played by the super-radial expansion responsible for the lower velocity. These new findings have relevant implications for the upcoming Solar Orbiter and Solar Probe Plus missions, and for turbulence measurements close to the Sun.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMSH42A..02D
- Keywords:
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- 2164 Solar wind plasma;
- INTERPLANETARY PHYSICSDE: 2169 Solar wind sources;
- INTERPLANETARY PHYSICSDE: 7509 Corona;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMYDE: 7524 Magnetic fields;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY