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Letter to the Editor
Outflow velocity of interplume regions at the base of Polar Coronal Holes
Received 2 May 2000 / Accepted 13 June 2000
We report on SUMER/SOHO observations at 1.05 of a well identified interplume region in a South Pole Coronal Hole. Combination of Doppler shifts and Doppler dimming measurements allowed to determine, for the first time, the total wind outflow velocity ( 67 km s-1) at this height. Our calculations of the outflow velocity benefit from co-spatial and almost co-temporal observations. This large outflow velocity is a strong argument in favour of the interplumes being the main source of the fast solar wind. We find that the mass flux density through the observed interplume is which yields at 1 AU with an expansion factor of 11.
Key words: Sun: corona Sun: solar wind Sun: UV radiation
Send offprint requests to: S. Patsourakos
Online publication: July 7, 2000