Analysis of Coronal H i Lyman-Alpha Measurements in a Polar Region of the Sun Observed in 1979
Abstract
Measurements of the intensities and spectral line profiles of resonantly scattered hydrogen Ly-alpha radiation have been used to determine hydrogen kinetic temperatures and electron densities between r = 1.5 and 2.2 solar radii in a polar region of the corona observed in 1979 near solar maximum. The mean temperature, 1.8 x 10 to the 6th K, in this region is significantly higher, by about 60 percent, than that obtained in a similar region observed in a 1980 rocket flight. The densities in these two polar regions are similar and are a factor of about 4 larger than in polar coronal holes observed at solar minimum. The flow velocities in both regions are most likely subsonic for r less than about 4 solar radii. The results reported here support the hypothesis that polar coronal holes observed at different times during the solar cycle can have different temperatures, densities, and possibly flow velocities.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 1986
- DOI:
- 10.1086/164424
- Bibcode:
- 1986ApJ...307..381W
- Keywords:
-
- Lyman Alpha Radiation;
- Polar Regions;
- Solar Corona;
- Solar Spectra;
- Electron Density (Concentration);
- Flow Velocity;
- Line Spectra;
- Solar Temperature;
- Ultraviolet Spectra;
- Solar Physics;
- SUN: CORONA;
- SUN: SPECTRA;
- ULTRAVIOLET: SPECTRA