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Astron. Astrophys. 359, L1-L4 (2000)

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Letter to the Editor

Outflow velocity of interplume regions at the base of Polar Coronal Holes

S. Patsourakos 1 and J.-C. Vial 1

Institut d'Astrophysique Spatiale, Université Paris XI - CNRS, Bât. 121, 91405 Orsay Cedex, France (spiros,vial@medoc-ias.u-psud.fr)

Received 2 May 2000 / Accepted 13 June 2000


We report on SUMER/SOHO observations at 1.05 [FORMULA] 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 ([FORMULA] 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 [FORMULA] which yields [FORMULA] 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

© European Southern Observatory (ESO) 2000

Online publication: July 7, 2000