Origin of the Solar Wind: Theory |
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Authors: | Fisk LA Schwadron NA |
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Institution: | (1) Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI, 48109-2143, U.S.A |
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Abstract: | A theory is presented for the origin of the solar wind, which is based on the behavior of the magnetic field of the Sun. The
magnetic field of the Sun can be considered as having two distinct components: Open magnetic flux in which the field lines
remain attached to the Sun and are dragged outward into the heliosphere with the solar wind. Closed magnetic flux in which
the field remains entirely attached to the Sun, and forms loops and active regions in the solar corona. It is argued that
the total open flux should tend to be constant in time, since it can be destroyed only if open flux of opposite polarity reconnect,
a process that may be unlikely since the open flux is ordered into large-scale regions of uniform polarity. The behavior of
open flux is thus governed by its motion on the solar surface. The motion may be due primarily to a diffusive process that
results from open field lines reconnecting with randomly oriented closed loops, and also due to the usual convective motions
on the solar surface such as differential rotation. The diffusion process needs to be described by a diffusion equation appropriate
for transport by an external medium, which is different from the usual diffusion coefficient used in energetic particle transport.
The loops required for the diffusion have been identified in recent observations of the Sun, and have properties, both in
size and composition, consistent with their use in the model. The diffusive process, in which reconnection occurs between
open field lines and loops, is responsible for the input of mass and energy into the solar wind.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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