Soft X-Ray and Microwave Observations of Hot Regions in Solar Flares
Abstract
Hot regions in solar flares produce X-radiation and microwaves by thermal processes. Recent X-ray data make it possible to specify the temperature and emission measure of the soft X-ray source, by using, for instance, a combination of the 1-8 Å (peak response at about 2 keV) and the 0.5-3 Å (peak response at about 5 keV) broad-band photometers. The temperatures and emission measures thus derived satisfactorily explain the radio fluxes, within systematic errors of about a factor of 3. Comparison of 15 events with differing parameters shows that a hot solar flare region has an approximately isothermal temperature distribution. The time evolution of the correlation in a single event shows that the hot material originates in the chromosphere, rather than the corona. The density must lie between 1010 and 2 × 1011 cm−3. For an Importance 1 flare, this implies a stored energy of roughly 2 x 1030-1029 ergs. A refinement of the data will enable us to choose between conductive and radiative cooling models.
- Publication:
-
Solar Physics
- Pub Date:
- March 1972
- DOI:
- 10.1007/BF00153899
- Bibcode:
- 1972SoPh...23..155H
- Keywords:
-
- Microwave;
- Flare;
- Thermal Process;
- Solar Flare;
- Emission Measure