论文标题
WISPR观察到的0.1 AU处的冠状质量弹性变形
Coronal mass ejection deformation at 0.1 au observed by WISPR
论文作者
论文摘要
尽管类似于通量绳索的冠状质量弹出（CMES）通常会自相似，但在观测和模拟中已经报道了沿其前部的变形。我们提供了一个证据表明，在电晕中自我相似的一段时间后，一个CME变形了。该事件是由多个白光成像仪在2021年1月20日至22日观察到的。在天气层成像仪的观察结果中，宽阔的成像仪的观测值很明显，用于太阳能探针Plus（WISPR），该观察者以$ \ sim $ 44小时的速度观察此CME。我们使用前拟合模型重建CME。在最初的几个小时里，观察结果与自相似的扩张一致，但后来在前面变平，形成了一个凹痕。我们的解释是，由于背景太阳风速的差异，CME在$ \ sim0.1 \ au $中变形。 CME在较高的纬度地区扩展更多，而背景太阳风更快。我们考虑了变形的其他可能原因，例如连贯性和慢模式冲击。 CME变形似乎在$ \ sim 0.5 \ au $时会导致16小时的到达时间错误。变形只有在WISPR观察中才明显，因此，它会被1〜AU冠冕所遗漏。这种变形可能有助于解释仅可用冠状动脉观察的事件中的到达时间。
Although coronal mass ejections (CMEs) resembling flux ropes generally expand self-similarly, deformations along their fronts have been reported in observations and simulations. We present evidence of one CME becoming deformed after a period of self-similarly expansion in the corona. The event was observed by multiple white-light imagers on January 20-22, 2021. The change in shape is evident in observations from the heliospheric imagers from the Wide-Field Imager for Solar Probe Plus (WISPR), which observe this CME for $\sim$ 44 hours. We reconstruct the CME using forward-fitting models. In the first hours, observations are consistent with a self-similar expansion but later on the front flattens forming a dimple. Our interpretation is that the CME becomes deformed at $\sim0.1\ au$ due to differences in the background solar wind speeds. The CME expands more at higher latitudes, where the background solar wind is faster. We consider other possible causes for deformations, such as loss of coherence and slow-mode shocks. The CME deformation seems to cause a time-of-arrival error of 16 hours at $\sim 0.5\ au$. The deformation is clear only in the WISPR observations and, it thus, would have been missed by 1~AU coronagraphs. Such deformations may help explain the time-of-arrival errors in events where only coronagraph observations are available.
