Authors: S. Hefti, H. Gruenwaldt, P. Bochsler, and M.R. Aellig
Reference: J. Geophys. Res., 105, 10,527-10,536, 2000.
Abstract:
We use the charge time-of-flight (CTOF) mass and charge spectrometer ot
the charge, element, and isotope analysis system (CELIAS) on board the
Solar and Heliospheric Observatory (SOHO) to determine the solar wind
oxygen freeze-in temperature T76 from the O7+ and
O6+ abundance ratios in the period from days 92 to 299 of
the 1996 (Carrington Rotations 1908 to 1912). The freeze-in
temperature is a conserved property of the solar wind because the
charge states do not charge after a distance of a few solar radii.
Therefore it is an ideal in situ diagnostic for remote sensing of the
inner solar corona. We determine the mean freeze-in temperature during
the selected period to be 1.6 X 106 K. We use it to map
coronal regions of different temperatures and to determine the
separation between such regions based on our observation of abrupt
transitions of the freeze-in temperature. We find a upper limit for
the separation in the inner corona of 1000 km.