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J. E. Littleton, E. E. Scime (Dept. of Physics, West Virginia Univ.), S. P. Gary, R. Skoug (Los Alamos National Lab), N. Lin (School of Physics and Astronomy, Univ. of Minnesota)
The Ulysses spacecraft has now completed passes over both solar poles during solar maximum. These observations and observations during solar minimum are part of more than ten years of measurements of solar wind ions and electrons. This paper presents an update on the measurements of the electron heat flux in the solar wind during solar maximum and compares its excessive decrease with distance from the Sun during both extremes in solar activity. We report on our continued examination of the electron heat flux for long-term correlations with the solar wind speed and with power in low frequency plasma waves. We continue to find that the electron heat flux, when scaled by R to the 2.9 power to account for its variation with distance from the Sun, is constant and independent of heliographic latitude and solar cycle. We continue to find that both during solar maximum and minimum there is no significant correlation between the electron heat flux and the solar wind speed, counter to the predictions of some theoretical models. We continue to confirm that there is no correlation of the electron heat flux with low frequency plasma wave activity and that consequently the whistler heat flux instability, long considered the best candidate to account for the heat flux decreasing more rapidly with distance than expected, does not play an important part in limiting the solar wind heat flux. We report on our attempts to examine other plasma wave instabilities that might account for this decrease.
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.