Letter to the Editor
On the outflow in an equatorial coronal hole
Max-Planck-Institut für Aeronomie, 37191 Katlenburg-Lindau, Germany
Corresponding author: L. D. Xia, email@example.com
Accepted: 7 January 2003
We report new observations concerning the source of the fast solar wind by directly comparing Doppler-shift maps of Ne7+ with charts of the photospheric magnetic field in an equatorial coronal hole, which was observed by SUMER/SOHO and NSO/Kitt Peak on November 5, 1999. The relationship between the velocity field, line intensity and magnetic network is discussed. Our data show that there are both dark and bright regions in this coronal hole as seen in the line. The larger blue shifts of the line are associated mainly with the darker region, where the strong magnetic flux with a single polarity is concentrated. Conversely, the smaller blue shifts are measured mainly in the brighter region, with an underlying mixed-polarity magnetic structure. These observational results are in agreement with the model prediction that the fast solar wind is initially accelerated in the coronal funnels, which are regions with globally open coronal fields rooted in the magnetic network.
Key words: Sun: corona / Sun: solar wind / Sun: UV radiation / Sun: magnetic fields
© ESO, 2003