Relation Between Polar Plumes and Fine Structure in the Solar Wind from Ulysses High-Latitude Observations
Abstract
Ulysses observations showed that pressure balance structures (PBSs) are a common feature in the high-latitude and high-speed solar winds near the solar minimum. PBSs have been hypothesized to be remnants of coronal plumes and to be related to network activity such as magnetic reconnection in the photosphere. This suggests that information on the magnetic structure of PBSs would help to study the relation between PBSs and polar plumes. We have investigated the magnetic structures of the 104 PBSs by applying a minimum variance analysis to Ulysses/Magnetometer data and by examining the pitch-angle distribution of energetic electrons measured with Ulysses/SWOOPS. We found that PBSs have relatively more tangential discontinuities rather than rotational from the minimum variance analysis and there is no difference between PBSs observed in north and south polar regions. From the analysis of energetic electron data, most PBSs also show local bi-directional electron flux or isotropic pitch-angle distribution expected in plasmoids or, less often, the distribution expected in association with current-sheet structures. This suggests the hypothesis that PBSs are generated due by network activity such as magnetic reconnection at the base of polar plumes.
- Publication:
-
Solar Wind Ten
- Pub Date:
- September 2003
- DOI:
- 10.1063/1.1618589
- Bibcode:
- 2003AIPC..679..255Y
- Keywords:
-
- 96.60.Vg;
- 96.60.Pb;
- 96.40.Fg;
- 96.50.Ci;
- Particle emission solar wind;
- Solar wind plasma;
- sources of solar wind