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Weaker solar wind from the polar coronal holes and the whole Sun
Author(s) -
McComas D. J.,
Ebert R. W.,
Elliott H. A.,
Goldstein B. E.,
Gosling J. T.,
Schwadron N. A.,
Skoug R. M.
Publication year - 2008
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2008gl034896
Subject(s) - coronal hole , solar wind , heliosphere , physics , corona (planetary geology) , ecliptic , coronal mass ejection , solar minimum , polar wind , magnetopause , solar cycle 22 , astronomy , polar , astrophysics , atmospheric sciences , solar cycle , plasma , astrobiology , venus , quantum mechanics
Observations of solar wind from both large polar coronal holes (PCHs) during Ulysses' third orbit showed that the fast solar wind was slightly slower, significantly less dense, cooler, and had less mass and momentum flux than during the previous solar minimum (first) orbit. In addition, while much more variable, measurements in the slower, in‐ecliptic wind match quantitatively with Ulysses and show essentially identical trends. Thus, these combined observations indicate significant, long‐term variations in solar wind output from the entire Sun. The significant, long‐term trend to lower dynamic pressures means that the heliosphere has been shrinking and the heliopause must be moving inward toward the Voyager spacecraft. In addition, our observations suggest a significant and global reduction in the mass and energy fed in below the sonic point in the corona. The lower supply of mass and energy may result naturally from a reduction of open magnetic flux during this period.