Solar ultraviolet continuum radiation - The photosphere, the low chromosphere, and the temperature-minimum region
Abstract
Solar disk-center intensity measurements are compared with theoretical values calculated for atmospheric models derived from the temperature distributions found by Vernazza et al (1976); generally good agreement is found with an atmospheric model having a minimum temperature of about 4150 K or possibly higher. Empirical opacity values including LTE departures and absorption coefficients which best represent the radiation field in the range 1460-2100 A are presented. It is shown that a contribution to the opacity from Fe I almost equal to the Si I opacity makes it possible to explain the observed center-to-limb contrast between 1525 and 1570 A and its fast change through 1570 A. However, the strong measured limb darkening as compared with the calculated variation from 1600 to 1682 A cannot completely be accounted for in terms of opacity and still preserve the agreement with the absolute center intensities.
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- November 1980
- DOI:
- 10.1086/190694
- Bibcode:
- 1980ApJS...44..273S
- Keywords:
-
- Continuous Radiation;
- Solar Atmosphere;
- Solar Flux Density;
- Solar Spectra;
- Solar Temperature;
- Ultraviolet Spectra;
- Atmospheric Models;
- Brightness Temperature;
- Chromosphere;
- Opacity;
- Photosphere;
- Radiation Distribution;
- Solar Physics