对2007年5月23日的一个CME的起源和初始阶段的观测研究

Observations of the Origin and Initiation of a CME on May 23rd 2007

利用多波段联合观测数据,综合分析研究了一个发生于2007年5月23日的日冕物质抛射(Coronal Mass Ejection,CME)爆发事件的起源和初始阶段的物理演化过程.该CME起源于活动区10956内的一个并没有严格地位于活动区极性反转线上的U形活动区暗条,该暗条首先被扰动,然后从中间部分开始缓慢上升.在暗条上升运动过程中,从极紫外和软X射线像上可观测到位于暗条上方的日冕磁环也在不断地上升并且有持续向外的扩张运动.最终,这些冕环和暗条一起爆发并伴随着一个位于暗条断开位置附近的日冕暗化区域的形成.这一爆发过程还伴随着一个静止轨道业务卫星(GeostationaryOperational Environmental Satellites,GOES)软X射线流量级别为B5.3的亚耀斑发生,该光斑显示出与CME之间具有在时间和空间上的紧密联系.与CME的"标准"磁流绳模型一致,这些太阳表面活动可以看作是CME的初始演化阶段在日面上的表现信号,并且该CME的亮前锋可能是由预先存在于暗条上方的冕环体系直接演化而来.另外,文中还讨论了与该事件相关的暗条爆发、耀斑、冕环扩张和消失以及日冕暗化之间的关系.

By means of multi-wavelength data, we present the observations of the origin and initiation of a coronal mass ejection （CME） occurring on May 23 2007 from the eruption of a U-shaped active-region filament in AR10956. The filament, which did not strictly reside above the polarity inversion line of the active region, was disturbed and then rose gradually from its middle part, during which its overlying coronal loops successively ascended and expanded in extreme-ultraviolet （EUV） and soft X-ray （SXR）. Eventually, the filament and these loops erupted along with the formation of a dimming region close to the preeruptive filament. The eruption was accompanied by the occurrence of a Geostationary Operational Environmental Satellites （GOES） X-ray class B5.3 subfiare, and showed closely spatial and temporal association with the CME. Consistent with the magnetic flux rope model of CMEs, these surface activities could be regarded as the on-disk signatures of the CME at the initial stage. The bright front of the CME was probably directly evolved from the preexisting coronal loops. The relationship between the filament eruption, flare, coronal loops expansion and coronal dimming is also discussed.