No CrossRef data available.
Published online by Cambridge University Press: 26 May 2016
Observations have been carried out using the oxygen VI multiplet ratio 1032/1038 Â from SUMER on SOHO. Analysis based on the Doppler dimming method shows that the outflow velocity in polar plumes is higher than that in the interplume region, contrary to many published suggestions. The addition of UVCS data for the interplume region, leads to a conclusion that the effective oxygen ion “temperature” in the radial direction has to rise to around 14 MK over the height range 1.5 to 1.8 R⊙.