Wind in the Solar Corona: Dynamics and Composition |
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Authors: | Ester Antonucci |
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Institution: | (1) INAF Osservatorio Astronomico di Torino, Torino, Italy |
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Abstract: | The dynamics of the solar corona as observed during solar minimum with the Ultraviolet Coronagraph Spectrometer, UVCS, on
SOHO is discussed. The large quiescent coronal streamers existing during this phase of the solar cycle are very likely composed
by sub-streamers, formed by closed loops and separated by open field lines that are channelling a slow plasma that flows close
to the heliospheric current sheet. The polar coronal holes, with magnetic topology significantly varying from their core to
their edges, emit fast wind in their central region and slow wind close to the streamer boundary. The transition from fast
to slow wind then appears to be gradual in the corona, in contrast with the sharp transition between the two wind regimes
observed in the heliosphere. It is suggested that speed, abundance and kinetic energy of the wind are modulated by the topology
of the coronal magnetic field. Energy deposition occurs both in the slow and fast wind but its effect on the kinetic temperature
and expansion rate is different for the slow and fast wind. |
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Keywords: | solar wind solar corona composition |
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