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Astron. Astrophys. 316, 355-367 (1996)

Constraints on high-speed solar wind structurenear its coronal base: a Ulysses perspective

W.C. Feldman1, B.L. Barraclough1, J.L. Phillips1, and Y.-M. Wang2

1 Los Alamos National Laboratory, MS D466, Los Alamos, NM 87545, USA
2 E.O. Hulburt Center for Space Research, Naval Research Laboratory, USA

Received 10 February 1996 / Accepted 2 May 1996

Abstract. Ulysses plasma data at high heliographic latitudes were studied to develop constraints on the structure of the corona at the base of the high-speed solar wind. Salient features of the flow poleward of img1.gif revealed: 1) low variances of all bulk flow parameters, 2) parameter values that agree with those measured during high-speed conditions in the ecliptic plane when all are scaled to 1AU, 3) the continuous presence of two interpenetrating proton streams that are not resolved in velocity space, 4) a single alpha-particle beam that travels at a speed that is close to the local Alfvén speed faster than the primary proton beam, 5) a proton temperature that is a factor of 2.4 times that of the electrons, and 6) a constant helium abundance that averages 4.4% , about half that inferred from helioseismic data in the solar convection zone. These data are combined with a host of other remote-sensing solar data and solar wind data to develop support for a model of a well-mixed solar atmosphere that is driven by reconnection-generated plasma-jet transients. In this model, acceleration of the solar wind to its terminal speed is complete within a heliocentric distance of about img2.gif .

Key words: solar wind - Sun: corona

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Last change: December 30, 1996
© European Southern Observatory (ESO) 1996