Three types of solar wind flow

The origin of the large-scale stream structure of the solar wind flow was studied using an experimental approach. Radio astronomy data obtained in 1997 were compared with SOHO optical observations of the solar corona and magnetic structures derived from the J.Wilcox Observatory Zeeman data. A correlative relation was obtained between the position of the transonic region of the solar wind and magnetic field strength at the solar corona level. This relation falls into three branches cor- responding to three types of the magnetic field structure: an open type with the field lines going in the interplanetary space, closed loop-like type and intermediate type including both configura- tions of field lines. The high-speed streams originate above the open configurations, while closed and intermediate configura- tions produce low-speed solar wind.