[[2]]Electrons precipitating into the polar regions of the Sun form the source of the strahl. When the magnetic lines of force are connected with the interplanetary magnetic field (IMF) in the appropriate direction, the strahl electrons are transported from the solar corona with energies of up to several hundred eV. When the Sun's magnetic field lines are not connected with the IMF, the strahl effect is blocked at that pole.[3]
References
1. ^1 {{cite book | author=Schrijver, Carolus J. | author2=Siscoe, George L. | date=2010 | title=Heliophysics: Evolving Solar Activity and the Climates of Space and Earth | page=219 | publisher=Cambridge University Press | isbn=0-521-11294-X }}
2. ^1 {{cite book | first=Tadanori | last=Ondoh | title=Science of space environment | editor=Tadanori Ondoh | editor2=Katsuhide Marubashi | publisher=IOS Press | date=2001 | isbn=4-274-90384-2 | page=161 }}