A REEXAMINATION OF THE EVIDENCE FOR RECONNECTION INFLOW

摘要

In the flare event of 1999 March 18, a threadlike structure observed in EUV Imaging Telescope images was found to move inward and collapse to an X-shaped configuration below the ejecta, strongly suggestive of the occurrence of magnetic reconnection. On the basis of the numerical results of a coronal mass ejection (CME) flare model, a similar threadlike structure in the Fe Ⅻ 195 A image is reproduced in this Letter. It is found that, as in the observations, the thread experiences an outward motion in the preflare phase, which is followed by an inward motion. Our simulation suggests that its formation and outward motion in the preflare phase result from the CME expansion; after the onset of the flare, the threadlike structure is always located on the upstream side of the interface between the reconnection inflow and outflow. Its apparent inward motion, which is several times slower than the in situ reconnection inflow, is mainly attributed to the rising motion of the reconnection X-point.