Solar Flares in the Extreme Ultraviolet. II. Comparisons with Other Observations
Abstract
Extreme-ultraviolet (300-1350 Å) observations of nearly 500 solar flares from the satellites OSO 4 and OSO 6 have been compared with data in X-ray and radio wavelengths. It is found that EUV flares are closely associated with nonthermal X-ray and microwave bursts. The EUV maximum intensity generally precedes the maximum intensity in Hα or soft X-rays by up to several minutes. The EUV e-folding rise time and peak intensity both depend on the X-ray burst characteristics. Nonthermal X-ray flares tend to be accompanied by strong, rapidly rising EUV bursts, while thermal X-ray events are usually associated with weaker, more slowly rising EUV flares. These relations are consistent with a picture of the flare in which the EUV radiation is produced thermally in a region of high (chromospheric) density, which is being heated by collisional losses of the nonthermal electrons responsible for the impulsive X-ray and microwave burst.
- Publication:
-
Solar Physics
- Pub Date:
- May 1972
- DOI:
- 10.1007/BF00231095
- Bibcode:
- 1972SoPh...24..180W
- Keywords:
-
- Microwave;
- Flare;
- Maximum Intensity;
- Rise Time;
- Solar Flare