Cranmer, S. R. 2005, ``UVCS Observations of Solar Wind and its Modeling,'' 6th Solar-B Science Meeting, Kyoto, Japan, November 8-11, 2005 (Invited Talk). [Talk viewgraphs, in Adobe PDF format, are available.]

ABSTRACT:

This presentation will review the dramatic new understanding of the solar wind that has come from the past decade of UVCS/SOHO observations, analysis, and theoretical work. In many ways, there is a key synergy between the two very different kinds of remote-sensing measurements discussed here. (1) The high-resolution solar disk measurements of Yohkoh and Solar-B reveal the complex lower boundary conditions for solar mass loss. (2) Coronagraph measurements in the wind's acceleration region (especially in combination with spectroscopy) allow the highly dynamic nonequilibrium evolution of the plasma to be followed as the asymptotic conditions in interplanetary space are established. Both kinds of observations are needed for a complete understanding of the expansion of the Sun's atmosphere. This presentation gives a brief survey of UVCS/SOHO results, including evidence for preferential acceleration of heavy ions in coronal holes, ion temperatures exceeding 100 million K at large heights, and extreme departures from Maxwellian velocity distributions in both fast and slow solar wind streams. UVCS also provided the first detailed plasma diagnostics of coronal mass ejections in the extended corona, yielding new insights into the roles of shock waves, current sheets, and helicity conservation in the evolution of solar eruptions.


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