Structure and spectrum of quiencent prominences. IV. The ultraviolet ionization continua of hydroden and helium.
Abstract
The formation of the ground-state ionization continua of hydrogen and neutral helium in quiescent prominences has been investigated by using isothermal and isobaric slab models. The hydrogen and helium ionization equilibria are dominated by the extreme ultraviolet radiation field incident on the prominence. The Lyman continuum brightness is dependent only on the incident radiation and the optical thickness of the prominence. The ratio of the intensity in the He I to the Lyman continuum is principally a function of the hardness of the incident radiation and the helium abundance and is only secondarily a function of the optical thickness of the slab and the gas pressure. The color temperatures of the continua, when corrected for optical depth effects, are good indicators of the electron temperature in the prominence. The slab models used in this study, which were developed to reproduce the visible spectrum hydrogen and helium lines, are in reasonable agreement with existing ultraviolet observations.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1983
- DOI:
- 10.1086/160965
- Bibcode:
- 1983ApJ...268..398H
- Keywords:
-
- Solar Prominences;
- Solar Spectra;
- Ultraviolet Spectra;
- Continuous Spectra;
- Helium;
- Hydrogen;
- Ionization;
- Lyman Spectra;
- Solar Physics