Origins of the Slow and the Ubiquitous Fast Solar Wind

We present in this Letter the first coordinated radio occultationmeasurements and ultraviolet observations of the inner corona below 5.5 Rs,obtained during the Galileo solar conjunction in January 1997, to establish theorigin of the slow solar wind. Limits on the flow speed are derived from theDoppler dimming of the resonantly scattered componentof the oxygen 1032 A and1037 A lines as measured with the UltraViolet Coronagraph Spectrometer (UVCS)on the Solar and Heliospheric Observatory (SOHO). White light images of thecorona from the Large Angle Spectroscopic Coronagraph (LASCO) on SOHO takensimultaneously are used to place the Doppler radio scintillation andultraviolet measurements in the context ofcoronal structures. These combinedobservations provide the first direct confirmation of the view recentlyproposed by Woo and Martin (1997) that the slow solar wind is associated withthe axes, also known as stalks, of streamers. Furthermore, the ultravioletobservations also show how the fast solar wind is ubiquitous in the innercorona, and that a velocity shear between the fast and slow solar wind developsalong the streamer stalks.Comment: 15 pages, LaTex, 6 jpg figures, accepted Aug. 28, 1997 for publication in the ApJ Letter