Coronal X-Ray Dimming in Two Limb Flares
Abstract
Yohkoh SXT observations of flares and large-scale arcade events frequently show coronal dimming accompanying X-ray brightening in long-duration events. The authors tentatively identify this with the process of field-line opening in the initial phase of a coronal mass ejection (CME), although few simultaneous coronagraph and soft X-ray observations have yet been described. The dimming signature may reduce the coronal soft X-ray intensity by as much as a factor of 2 - 3, and thus has a higher contrast than the cavity often seen in white-light CME observations. In the cases examined thus far, the authors find a close match between the onsets of X-ray brightening and coronal dimming, suggesting a close physical relationship. The dimming appears (in movie representations) to result from outward expansion; highly structured features (multiple loops) are recognizable in the dimming regions of some events, suggesting that the soft X-ray data may be used to characterize the velocity field of the expansion.
- Publication:
-
Astronomical Society of the Pacific Conference Series
- Pub Date:
- 1996
- Bibcode:
- 1996ASPC..111..379H
- Keywords:
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- Solar Corona: Solar X-Ray Flares;
- Solar Coronal Loops: X-Ray Surveys