Emitting region of sodium lines in solar prominences
Abstract
The emission spectra of hydrogen and sodium atoms in the cool part of prominence models which satisfy simultaneously the constraints of radiative transfer, statistical equilibrium and charge-particle conservations have been calculated. In the considered range of the model parameters, emission strengths of H-alpha and NaI D lines increase with temperature and total number density. Low-pressure models raise the ionization rate significantly but yield very weak NaI D line intensities, since these model prominences contain small amounts of free electrons and sodium atoms which have a deep relation with the formation of sodium lines. It is found that sodium D lines should be emitted in the high pressure region of prominences, and that their intensities are difficult to attain in the cool core of any model prominence with a temperature as low as 4000 K. In order to explain consistently the spectral emissions of H-alpha and NaI D lines observed in quiescent prominences, a total number density higher than 4 x 10 to the 11th/cu cm and a temperature over 5000 K are required, at least in the cool part of prominences.
- Publication:
-
Solar Physics
- Pub Date:
- 1987
- DOI:
- 10.1007/BF00193066
- Bibcode:
- 1987SoPh..114...47K
- Keywords:
-
- Emission Spectra;
- Sodium;
- Solar Prominences;
- Solar Spectra;
- Abundance;
- H Alpha Line;
- Hydrogen;
- Stellar Models;
- Solar Physics