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Modeling the Solar Wind in Quiet Regions

 

When observed on the solar disk, the quiet sun, also called unstructured corona, is the diffuse emission characterized by large scale closed magnetic field structures, outside coronal holes and active regions (e.g., Withbroe 1988). The extension of the quiet sun into the outer corona, as seen in an eclipse photograph, consists of closed magnetic structures underlying open field lines that define the coronal structure well above the coronal base. The quiet sun might be the source region of the low speed solar wind. Since the observed intensity from emission lines in the quiet sun is larger than that in coronal holes, the density and temperature are expected to be higher in the former region. Consequently, it should be possible to map these regions to larger heliocentric distances from the solar surface than coronal holes.

We propose here to measure plasma parameters in different quiet sun regions, both as a function of heliocentric distance, and as a function of latitude. Due to the expected low outflow speeds in the quiet sun, the measurements of the Doppler dimming of the O VI lines, and other minor ions, will be particularly important. These measurements will make it possible to construct empirical temperature, density, and velocity profiles in different quiet sun regions. Line widths will yield information on the behavior of the nonthermal broadening as a function of heliocentric distance.

Modeling the Solar Wind in Quiet Regions



Peter Smith
Fri Jan 17 12:11:15 EST 1997