X-ray and radio manifestations of a solar eruptive event

We report on a study of the changes in the vicinity of a disappearing solar filament (DSF) that occurred on 1993 April 30. The DSF was associated with a long duration X-ray event (LDE) observed by the GOES and Yohkoh spacecraft. A detailed analysis of the X-ray images obtained by the Yohkoh Soft Xray Telescope revealed that X-ray manifestations of the eruption were wide-spread: (i) X-ray enhancement over a coronal volume several times larger than that of the eruption region, probably the X-ray counterpart of a coronal mass ejection (CME), (ii) Xray ejecta accelerating to 670 km s−1 into the corona, and (iii) quasi-stationary X-ray loops as in long decay events (LDEs) were observed. One of the important findings of this study is the large-scale X-ray enhancement which we identify with the frontal structure of a CME, apart from the well-known X-ray ejecta and post-eruption arcade formation. There is evidence for triggering of a sympathetic flare in an adjoining active region due to the X-ray ejecta from the eruption region. Stationary metric radio continuum observed by the Nançay Radioheliograph was found to be associated with the brightest X-ray loops that formed following the filament eruption. The unpolarized continuum radio emission was found to be bremsstrahlung radiation from the hot plasma observed in X-rays. The event was also associated with a low frequency metric type II radio burst due to a coronal shock wave from the eruption region. The onset time of the type II emission precludes the possibility of a CME-driven shock causing it. Although we do not have positional information for the type II burst, we found that the X-ray ejecta was fast enough to drive the coronal shock. We confirmed this by comparing the speed of the X-ray ejecta with the shock speed obtained from the radio data which agreed within 10%.