SCIENCE OBJECTIVE: We propose to study the sources of fast and slow
solar wind by investigating how the flux tubes change from a high-speed
to a low-speed region. We will select a polar hole with a clearly-defined streamer region nearby and study both regions and the boundary between the polar coronal hole and the surrounding quiet Sun region from the limb to UVCS heights. We aim to measure how the plasma physical properties change between the two wind regions, and with height, and how the flux tubes expand with
heliocentric distance. In particular, this campaign will study the evolution of the transition from fast to slow wind source regions as a function of time and heliocentric distance from the limb and will provide important experimental
constraints to theoretical models.
The present campaign will advance previous studies (e.g. Cranmer et al.
1999; Strachan et al. 2002; Landi et al. 2007) by examining the fast and slow
source regions and its transition as follow:
1 - centering the field of view on the boundary between the coronal hole
and the quiet Sun
2 - using a much larger set of spectral lines
3 - extending the study to 2-4 R(sun) above the limb. |
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