The Solar Wind.pdf

• The Archimedean spiral associatedwith slow streams is curved morestrongly than for a fast stream.• Because field lines are not allowedto intersect at some point aninteraction region develops betweenfast and slow streams. Since bothrotate with the Sun these are calledcorotating interaction regions(CIR).• On the Sun there is an abruptchange in the solar wind speeds butin space the streams are spread out.• At the interface between fast andslow streams the plasma iscompressed.• The characteristic propagationspeeds (the Alfven speed and thesound speed) decrease.• At some distance between 2AU and3AU the density gradient on bothsides of the CIR becomes large anda pair of shocks develop.• The shock pair propagate awayfrom the interface.– The shock propagating into theslow speed stream is called aforward shock.– The shock propagating into thefast wind is called a reverseshock.