Document Type

Article

Publication Title

Geophysical Research Letters

Publisher

American Geophysical Union

Publication Date

7-1-1999

Volume

26

Issue

13

Disciplines

Astrophysics and Astronomy

Abstract

Ulysses observations of the high-latitude solar wind have shown that on time scales of < 1 day, the polar wind is dominated by pressure balance structures (PBSs). Fluctuations of the plasma beta within PBSs appear to be strongly correlated with fluctuations in the helium abundance. The correlation occurs in both the northern and southern hemispheres. In addition, a mechanism is apparently at work in the high-latitude solar wind that dissipates the beta/He correlation over a distance of a few AU. Solar wind composition is established at the base of the corona; thus, the He abundance signature strongly suggests the observed solar wind PBSs are associated with structures low in the solar atmosphere. In particular, high-beta structures appear to originate in locations of enhanced He abundance. We suggest an interpretation of the high-beta portion of PBSs as the solar wind extensions of polar plumes.

DOI

10.1029/1999GL900368

Comments

© 1999 American Geophysical Union. View original published article at 10.1029/1999GL900368.

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