Simulated O VI Doppler dimming measurements of coronal outflow velocities.
Abstract
The authors investigate the possibility of determining O5+ outflow velocities by using a Doppler dimming analysis of the resonantly scattered intensities of O VI λ1031.9 and λ1037.6. The technique is sensitive to outflow velocities, W, in the range 30 < W < 250 km s-1 and can be used for probing regions of the inner solar corona, where significant coronal heating and solar wind acceleration may be occurring. These velocity measurements, when combined with measurements of other plasma parameters (i.e., temperatures and densities of ions and electrons), can be used to estimate the energy and mass flux of O5+. In particular, it may be possible to locate where the flow changes from subsonic to supersonic and to identify source regions for the high- and low-speed solar wind. The velocity diagnostic technique is discussed with emphasis placed on the requirements needed for accurate outflow velocity determinations. Model determinations of outflow velocities based on simulated Doppler dimming observations are presented.
- Publication:
-
Coronal Streamers, Coronal Loops, and Coronal and Solar Wind Composition
- Pub Date:
- November 1992
- Bibcode:
- 1992ESASP.348..121S
- Keywords:
-
- Doppler Effect;
- Flow Velocity;
- Solar Corona;
- Space Plasmas;
- Mathematical Models;
- Plasma Diagnostics;
- Resonance Scattering;
- Velocity Measurement;
- Solar Physics