A MALTESE CROSS-SHAPED FLARE OF JUNE 15, 2001

摘要

The solar flare in NOAA 9502 began on June 15, 2001 at 10:01 UT (S26E41). Its importance was 1N in optical band, M6.3 in X-rays and in radio band it was accompanied by a burst of 5800 units at 245 MHz and 130 units at 300 MHz. Spectra in D3 of He, Hα and CaII 8542 A lines including the slit-jaw images were detected at the Multichannel Flare Spec-trograph (MFS) from the early beginning of the flare with temporal resolutions 25 images per second. In addition, in Hα line the series of Stokes U/I parameter were observed. To the most spectacular features of the flare belongs the symmetric shape of emission ribbons configured into a Maltese cross. While at the cross arms one could detect standard emission line profiles, there appeared a compact feature with a very broad emission line profile in the center of the cross. It gives us an evidence about a certain type of singularity of this particular point. The very broad emission profile can be explained as by means of a high microturbulence. We describe and discuss another characteristics and particularities of this flare including the result of spectropolarimetric measurements that can be an evidence for the accelerated particle beams interaction with dense chromospheric layers.