Hot plasma motion observed in sigmoidal loop during the flare in NOAA 8323 active region on 4 September 1998 Original Research Article

We present a study of the hot plasma motion in a sigmoidal loop during the C2.2 class solar flare in NOAA 8323 active region on 4 September 1998. In our work we analysed spectra and images taken with Wrocław Large Coronagraph coupled with Multi-Channel Subtractive Double Pass Spectrograph and Hα camera, Yohkoh Soft X-ray Telescope, Yohkoh Bragg Crystal Spectrometer, whole-disk integrated X-ray flux measurements made by GOES and INTERBALL RF15-I photometer as well as radio flux measurements taken with Ondrejov RT3 radiotelescope. The SXT images reveal an expansion of the X-ray flare kernels along the both legs of the sigmoidal loop toward the loop-top. Assuming circular shape of the loop we calculated full velocity vectors of the kernels and their line-of-sight components. The calculated line-of-sight velocities were of the same order as velocities evaluated from BCS spectra. We suppose that observed event was direct manifestation of the plasma evaporation in the flaring loop.