The core electron temperature profile between 0.5 and 1.0 AU in the steady-state high speed solar wind
Abstract
The radial dependence of the core electron temperature in the steady-state high speed solar wind between 0.5 and 1.0 AU is measured using Mariner 10 and Imp 6, 7, and 8 instrumentation. The observed temperature profile is best characterized by two separate power-law functions which apply in the radial ranges between 0.47 and 0.62 AU and between 0.62 and 1.0 AU, respectively. The separate values of the logarithmic temperature derivatives are αi=-1.14+/-0.24 and α0=+0.28+/-0.13, respectively. Whereas the inner value of α, αi, agrees with a previous estimate (αc =-0.9+/-0.1) using data measured within high speed compression zones of simple high speed streams, the outer value of α, α0, is significantly more positive than any previous theoretical or experimental estimate. A likely explanation is a modest thermal coupling between the protons and electrons by way of kinetic instabilities driven by the generally observed, double streaming proton velocity configurations. The core electron temperature of about 1×105 K measured using Mariner 10 instrumentation at 0.47 AU is also significantly less than any value predicted by current models of the high speed solar wind at that distance.
- Publication:
-
Journal of Geophysical Research
- Pub Date:
- August 1979
- DOI:
- 10.1029/JA084iA08p04463
- Bibcode:
- 1979JGR....84.4463F
- Keywords:
-
- Electron Energy;
- Radial Distribution;
- Solar Wind Velocity;
- Temperature Profiles;
- Cores;
- Flow Characteristics;
- Mariner 10 Space Probe;
- Satellite-Borne Instruments;
- Steady State;
- Temperature Gradients