科研之友
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摘要
The limb flare on 1992 January 13, the so-called Masuda flare, has stimulated scientists to refine theory of solar flares based on two-dimensional magnetic reconnection. This is primarily because of the hard X-ray (HXR) source seen above the clearly defined flare loop, and the outward motions in soft X-rays (SXRs) interpreted as "plasmoid" ejections. We have revisited Yohkoh HXR and SXR data for this and other limb flares and found that the Masuda flare is still unique in terms of the location and spectral properties of the coronal HXR source. However, the outward motions in SXR outside the flare loop may not be as simply characterized as plasmoid ejections as in other flares, nor are they particularly fast. The motions appear complex partly because we also see trans-equatorial loops in motion, one of whose legs anchors close to the main flare loop. It is possible that these large-scale loops represent post-flare loops, and that the flare may also be explained in terms of three-dimensional quadrupolar reconnection, similar to those flares where a pair of two loops exchange their footpoints through magnetic reconnection. It appears that expansion and brightening of large-scale loops offset from the main flare loop are not common, possibly providing a reason for the unusual coronal HXR source in the Masuda flare.
- 出版日期2010-12-10
