Authors: H. Gruenwaldt, M. Hilchenbach, E. Marsch, P. Bochsler, and F. Ipavich
Reference: Submitted Solar Wind 9 Paper
Abstract:
The classical link between the frozen-in solar wind ion charge
distribution and the inferred coronal electron temperature has been ruled
for long by the asumption of a Maxwellian velocity distribution of the
electrons. After theoretical negotiation of this assumption (Owocki &
Scudder 1983), recent experience from the observation of O VI lines by
UV instruments on SOHO has raised serious doubts as to a considerably
overestimated temperature, in contrast to the very low upper limits
of O5+ as solar wind constituent seen by Ulysses in high
speed wind. From CELIAS/CTOF data it has now been possible to measure
abundance figures for solar wind conditions of slow to moderate speed from
near streamer belt source regions, rising with growing speed to values
almost an order of magnitude higher than the limits seen before. The
coincident presence of high and low O charge states is understood by
energetic tail electrons ionising, and cool core electrons being part
of radiative recombination.