EUV continua of solar flares 1420 - 1960 Å.
Abstract
Measurements of absolute continuum intensities in the wavelength range 1420-1960 A are presented for the SN subflare of 1973 August 9 and the 2B flare of 1973 September 7, observed from the NRL spectrograph aboard Skylab. Continuum measurements are also given for two active-region plages, which are used for background nonflaring levels. Major enhancement of the flare continuum intensity above the plage backgrounds occurs in the Si I 3P and 1D continua. The observed brightness-temperature minimum of the plages is approximately 310 K above the quiet-sun minimum, and occurs at longer wavelength. The earliest flare brightness-temperature minima are approximately 200 K above the plage minimum, and also at longer wavelength. The observed decay time of the flare brightness temperature, which is comparable to the Solrad 9 X-ray decay time, is much longer than the Ulmschneider radiative relaxation time for the 1973 September 7 flare and marginally longer for the 1973 August 9 flare, suggesting continuous excess heating of the plage temperature minimum region throughout the period of our flare observations.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 1979
- DOI:
- 10.1086/156775
- Bibcode:
- 1979ApJ...227..645C
- Keywords:
-
- Faculae;
- Far Ultraviolet Radiation;
- Solar Flares;
- Solar Spectra;
- Brightness Temperature;
- Skylab Program;
- Stellar Spectrophotometry;
- Solar Physics;
- Extreme UV:Solar Flares;
- Extreme UV:Solar Plages;
- Solar Flares:UV Spectra