Publication List of the Solar-Heliospheric Research Group at the University of Michigan: Publications 5e92

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author T.H.Zurbuchen

co-authors S.Hefti, L.A.Fisk, G.Gloeckler, N.A.Schwadron, R.von Steiger

title "The Transition from Fast and Slow Solar Wind: Experimental Constraints on Solar Wind Theories"

journal other

volume --

page --

year --

group ACE, Ulysses

keywords other

abstract It is generally believed that fast solar wind originates in coronal holes and expands to low latitude. Slow solar wind, however, originates from closed magnetic field regions. This simple model has been repeatedly challenged based on both solar and heliospheric observations. For example, it has been proposed that the solar wind could expand more radially from all solar latitudes. Since many of the dynamic parameters of the solar wind are changed during its expansion through the heliosphere, it is hard to test those theories in situ. However, using charge state and elemental composition data as measured with Ulysses-SWICS and ACE-SWICS, we are able to get a very detailed view of various solar wind streams which are not affected by processes occurring away from the sun. We will present Ulysses-SWICS and ACE-SWICS data which indicate that the fast and slow solar wind are fundamentally different. It will be shown that the transition from one regime into the other is very abrupt and occurs on the shortest time-resolution of the sensors. We will present new data and discuss them in the framework of the theories mentioned above.

cross-references none

type Abstract

Entered swics.engin.umich.edu 1998/07/29 16:00

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author	T.H.Zurbuchen
co-authors	S.Hefti, L.A.Fisk, G.Gloeckler, N.A.Schwadron, R.von Steiger
title	"The Transition from Fast and Slow Solar Wind: Experimental Constraints on Solar Wind Theories"
journal	other
volume	--
page	--
year	--
group	ACE, Ulysses
keywords	other
abstract	It is generally believed that fast solar wind originates in coronal holes and expands to low latitude. Slow solar wind, however, originates from closed magnetic field regions. This simple model has been repeatedly challenged based on both solar and heliospheric observations. For example, it has been proposed that the solar wind could expand more radially from all solar latitudes. Since many of the dynamic parameters of the solar wind are changed during its expansion through the heliosphere, it is hard to test those theories in situ. However, using charge state and elemental composition data as measured with Ulysses-SWICS and ACE-SWICS, we are able to get a very detailed view of various solar wind streams which are not affected by processes occurring away from the sun. We will present Ulysses-SWICS and ACE-SWICS data which indicate that the fast and slow solar wind are fundamentally different. It will be shown that the transition from one regime into the other is very abrupt and occurs on the shortest time-resolution of the sensors. We will present new data and discuss them in the framework of the theories mentioned above.
cross-references	none
type	Abstract
Entered swics.engin.umich.edu 1998/07/29 16:00