Diagnostics of hot thermal plasma in flare-associated X-ray ejections Original Research Article

This is the first analysis of the soft X-ray spectra of flare-associated X-ray ejections. For this aim, the Yohkoh Bragg Crystal Spectrometer data recorded before two behind-the-limb flares were selected. These flares came into view from behind the solar limb but their occurrence was preceded by an X-ray ejection which expanded faster. In consequence, for several minutes the X-ray ejection was seen alone, without the presence of the brighter flare. Parameters of the plasma obtained from a fitting of synthetic spectra to observed spectra are presented and compared to images from the Yohkoh Soft X-ray Telescope. The presence of a minor fraction of the very hot (∼30 MK) thermal plasma in X-ray ejections is confirmed. High values of the non-thermal line broadening are caused by a large extension of X-ray ejections.