Reconnecting and Evaporating Flare Model Observed in the Flare of AR7186 of 1992 June 4
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Abstract
A di rect observation of a magnetic reconnecting and the chromosphere evaporating processes occurred in the flare of AR7186 of 1992 June 4, and observed by both the Soft X-ray Telescope(SXT)aboard the Yohkoh spacecraft and the Solar Flare Telescope (SFT, NAOJ, Mitaka), are reported in this article. The processes could be described as follows:Anactive Hα filament ascended and disappeared gradually. The brightening of the intersection between two mutually crossed coronal loops that spanned the filament implied that the current sheet formed and the reconnection onset in the tangential boundary between the loops. The rising of the reconnected loop marked the inflow, while the brightness of the foot-points of the reconnected loops and the surges that rooted the foot-points marked the outflow. Both of the inflow and the outflow were necessary for the reconnection. When the thermal plasma flowed out from the current dissipation region to cause the reconnected loops and their foot-points brig htening, the Hαflare kernels were simultaneously occurred, and the positions of the kernels were corresponding to the foot-points of the reconnected loops. The reconnected coronal loop disappearance implied the reconst ruction of the magnetic field configuration. Moreover, the fact that the coronal surge, which rooted in the foo t-points of the reconst ructed loops, changed its ejected directions indicated that the magnetic field of the reconst ructed loop suffered from opening. The SXR emission and the coronal post-flare loop occurrences were observed in the following order. First, at the very beginning of the flare, the soft X-ray emission came from foot softhe reconnected coronal loop. Then, at the flare maximum, the position of the emission changed to legs and tops of the reconst ructed loops.Finally, when the flare ended, the emission concentrated within the reconstructed loop-tops. The picture of the SXR emission processes indicated the characteristics and nature of evaporation:heated chromosphere material evaporated from the chromosphere up to the corona. In the last section of the article, the reconnecting and evaporating flare model deduced from the flare observations is proposed. Also, some possible time scales of sub-courses in the flare process are discussed.
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