Oxygen freeze-in temperatures measured with SOHO/CELIAS/CTOF
Abstract
We use the charge time-of-flight (CTOF) mass and charge spectrometer of 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 229 of 1996 (Carrington Rotations 1908 to 1912). The freeze-in temperature is a conserved property of the solar wind because the charge states do not change 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 1.6×106K. 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.
- Publication:
-
Journal of Geophysical Research
- Pub Date:
- May 2000
- DOI:
- 10.1029/1999JA900384
- Bibcode:
- 2000JGR...10510527H
- Keywords:
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- Interplanetary Physics: Sources of the solar wind;
- Solar Physics;
- Astrophysics;
- and Astronomy: Corona;
- and Astronomy: Transition region