Coronal temperatures, heating, and energy flow in a polar region of the sun at solar maximum
Abstract
The profiles of resonantly scattered Lyman-alpha coronal radiation have been used to determine the hydrogen kinetic temperature from 1.5 to 4 solar radius from the center of the polar region of the corona observed in 1980 at solar maximum. Hydrogen temperatures derived from the line profiles were found to decrease with height from 1.2 million K at r = 1.5 solar radii to 600,000 K at r = 4 solar radius. Comparison of the measured kinetic temperatures with predictions from a semiempirical two-fluid model showed evidence of a small amount of heating or a nonthermal contribution to the motions of coronal protons between 1.5 and 4 solar radius. The widths of the profiles confirmed an upper limit of 110 + or - 15 km/s on the rms magnitude of the line-of-sight component of velocities between 1.5 and 4 solar radius. Density measurements obtained in situ in the solar wind in the ecliptic were used to locate the sources of low speed and high-speed winds in the polar region. An eclipse photograph of the corona at solar maximum is provided.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1985
- DOI:
- 10.1086/163531
- Bibcode:
- 1985ApJ...297..324W
- Keywords:
-
- Energy Distribution;
- Plasma Heating;
- Solar Activity;
- Solar Corona;
- Solar Radiation;
- Solar Temperature;
- Lyman Alpha Radiation;
- Magnetohydrodynamic Waves;
- Maxima;
- Solar Wind Velocity;
- Spectral Line Width;
- Vertical Distribution;
- Solar Physics