The Magnetic Environment of a Stealth Coronal Mass Ejection
The Magnetic Environment of a Stealth Coronal Mass Ejection
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DOI：
10.3847/1538-4357/abd2bf
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发表时间：
2020-12
期刊：
影响因子：
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通讯作者：
J. O’Kane;C. Mac Cormack;C. Mandrini;P. Démoulin;L. Green;D. Long;G. Valori
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文献类型：
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作者：
J. O’Kane;C. Mac Cormack;C. Mandrini;P. Démoulin;L. Green;D. Long;G. Valori
隐形日冕物质抛射(CME)由于其相对较高的发生率和对空间天气的影响，正在引起人们越来越多的兴趣。然而，典型的CME信号，如极端紫外线暗淡和喷发后拱廊，很难识别，需要广泛的图像处理技术。这些微弱的观测信号意味着，目前人们对这些事件的物理学知之甚少。我们对2011年3月3日发生的隐形CME的磁场构型进行了广泛的研究。在隐形CME源活动区(AR)观察到了三个不同的耀斑带形成过程。两次发生在火山喷发之前，表明发生了磁性重联，形成了即将喷发的结构。第三次发生在STEREO-B 171ä数据中观测到的空洞喷发附近的时间；这随后成为日冕仪数据中观测到的传播CME的一部分。我们使用日冕磁场的局部(笛卡尔)模型和全球(球面)模型，并通过观测分析加以补充和验证。我们发现了日冕零点的证据，从它的邻域计算出的场线将隐形的CME源区连接到北半球的两个AR。我们的结论是，零点处的重联通过移除稳定喷发前结构的场来帮助隐形CME的喷发。这种隐形的日冕物质抛射尽管信号微弱，但具有其他日冕物质抛射的主要特征，而且它的爆发是由类似的机制驱动的。
Interest in stealth coronal mass ejections (CMEs) is increasing due to their relatively high occurrence rate and space weather impact. However, typical CME signatures such as extreme-ultraviolet dimmings and post-eruptive arcades are hard to identify and require extensive image processing techniques. These weak observational signatures mean that little is currently understood about the physics of these events. We present an extensive study of the magnetic field configuration in which the stealth CME of 2011 March 3 occurred. Three distinct episodes of flare ribbon formation are observed in the stealth CME source active region (AR). Two occurred prior to the eruption and suggest the occurrence of magnetic reconnection that builds the structure that will become eruptive. The third occurs in a time close to the eruption of a cavity that is observed in STEREO-B 171 Å data; this subsequently becomes part of the propagating CME observed in coronagraph data. We use both local (Cartesian) and global (spherical) models of the coronal magnetic field, which are complemented and verified by the observational analysis. We find evidence of a coronal null point, with field lines computed from its neighborhood connecting the stealth CME source region to two ARs in the northern hemisphere. We conclude that reconnection at the null point aids the eruption of the stealth CME by removing the field that acted to stabilize the preeruptive structure. This stealth CME, despite its weak signatures, has the main characteristics of other CMEs, and its eruption is driven by similar mechanisms.