Oxygen freeze-in temperature measured by SOHO/CELIAS

S. Hefti, P. Bochsler, H. Grünwaldt, M. Aellig, D. Hovestadt, M. Hilchenbach, F. M. Ipavich, R. Kallenbach, P. Wurz, the CELIAS team.

Paper presented at the AGU Spring Meeting, 27-30, May, 1997, Baltimore, USA

We determine O7+ and O6+ fluxes with the charge- and mass- spectrometer CTOF of the CELIAS instrument on board SOHO to derive the freeze-in temperature of oxygen charge states. It is well known that the freeze-in temperature is a sensitive measure of the den- sity and temperature of the corona and thus reveals information about the structure of the latter. The unprecedented high time-resolution of the CTOF data makes it possible to use the freeze-in temperatures to look for small-scale structures in the slow solar wind and to relate them to features observed in the inner corona and in the solar atmo- sphere. The freeze-in temperature is especially suited for such a type of investigation, because the charge state distributions remain essentially unchanged from a few solar radii to 1 AU, in contrast to kinetic solar wind properties.

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Last Update: March 20, 1997, Peter Wurz