Ion energy equation for the high-speed solar wind: Ulysses observations

W. C. Feldman, B. L. Barraclough, J. T. Gosling, D. J. McComas, P. Riley, B. E. Goldstein, A. Balogh

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17 Scopus citations


Ulysses data in the high-speed solar wind that cover a wide range of latitudes centered on the solar poles were studied to test whether a polytrope law can be used to close the ion energy equation. Three approaches were taken. We determined the correlation between proton temperature and density (1) in the free expansion of the high-speed solar wind between 1.5 and 4.8 AU, (2) in steepened microstreams at high latitudes, and (3) at the edges of the equatorial band of solar wind variability. Strong correlations were observed in all data subsets that are consistent with a single polytrope relation, Tp = aNp(γ*-1) where our best estimate for γ* is between 1.5 and 1.7. The best fitting relation is Tp = (2.0 ± 0.13) × 105 Np0-57.

Original languageEnglish (US)
Article number98JA00963
Pages (from-to)14547-14557
Number of pages11
JournalJournal of Geophysical Research: Space Physics
Issue numberA7
StatePublished - 1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Astronomy and Astrophysics
  • Oceanography


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