Spectral analysis of the optical continuum in the 24 April 1981 flare
Abstract
Spectrograph and multiple-band polarimeter observations of the 24 April 1981 white-light flare indicate the presence of an optical continuum with intensity increasing strongly below 4000 Å. The flare emission (lines and continuum combined) is unpolarized and, at 3600 Å, exceeds the brightness of the background solar surface by 360%. Analysis of the spectrum between 3600 and 8200 Å, at a location three arc sec from the brightest point in the kernel, yields a probable temperature of 6700 K for the continuum emitting layer. The wavelength dependence of the continuum indicates emission by both negative hydrogen (H−) and Balmer continuum, with the H− probably originating in the upper photosphere at a height (above τ5000 Å = 1) in the range 200-300 km. Analysis of the Balmer lines and continuum yields an electron density 5.3 × 1013 cm−3 and a second-level hydrogen column density 1.1 × 1016 cm−2. The peak radiative output integrated over wavelength is 6.1 × 1027 erg s−1. The observed continuum intensity, if originating at a height of 300 km, implies an energy loss rate of 103 erg s−1 cm−3.
- Publication:
-
Solar Physics
- Pub Date:
- June 1983
- DOI:
- 10.1007/BF00148655
- Bibcode:
- 1983SoPh...85..285N
- Keywords:
-
- Balmer Series;
- Solar Flares;
- Solar Spectra;
- Spectrum Analysis;
- Brightness;
- Electron Density (Concentration);
- Opacity;
- Solar Temperature;
- Solar Physics;
- Flare;
- Energy Loss;
- Loss Rate;
- Probable Temperature;
- Column Density