Switchback deflections beyond the early parker solar probe encounters
Switchback deflections beyond the early parker solar probe encounters
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超越早期帕克太阳探测器遭遇的之字形偏转
DOI：
10.1093/mnras/stac2477
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发表时间：
2022
影响因子：
4.8
通讯作者：
T. Woolley
中科院分区：
文献类型：
--
作者：
R. Laker;T. Horbury;L. Matteini;S. Bale;J. Stawarz;Lloyd D. Woodham;T. Woolley
反转是太阳风中的AFLVéNic波动，它在磁场方向上表现出很大的旋转。从帕克太阳探测器(PSP)的前两次太阳相遇中观察到的结果已经形成了所描述的许多回转特性和产生机制的基础。然而，这些早期的数据可能并不能代表典型的近太阳太阳风，从而影响了我们目前对这些现象的理解。定义回切特性的一个因素是磁偏转方向。在第一次太阳相遇期间，这主要是在最长的折返的切线方向上，这已经被讨论为几种折返产生方法的证据和可检验的预测。在这项研究中，我们重新检查了在前八次PSP遭遇期间折返的偏转方向，以确认系统偏转方向的存在。我们首先识别磁场中超过阈值偏转的回转，并确认先前的发现，即它们是弧极化的。与PSP第一次相遇的早期结果一致，我们发现一组较长的折返倾向于在几个小时内偏转到同一方向。然而，与前人的研究相比，我们发现这些偏转并不存在唯一的方向，尽管几次太阳相遇显示出偏转方向上的不均匀分布，并略有偏向于切向。这一结果表明了回转产生的系统磁场构型，这与交换重联作为源机制是一致的，尽管这一新证据不排除其他机制，如波模的扩展。
Switchbacks are Aflvénic fluctuations in the solar wind, which exhibit large rotations in the magnetic field direction. Observations from Parker Solar Probe’s (PSP’s) first two solar encounters have formed the basis for many of the described switchback properties and generation mechanisms. However, this early data may not be representative of the typical near-Sun solar wind, biasing our current understanding of these phenomena. One defining switchback property is the magnetic deflection direction. During the first solar encounter, this was primarily in the tangential direction for the longest switchbacks, which has since been discussed as evidence, and a testable prediction, of several switchback generation methods. In this study, we re-examine the deflection direction of switchbacks during the first eight PSP encounters to confirm the existence of a systematic deflection direction. We first identify switchbacks exceeding a threshold deflection in the magnetic field and confirm a previous finding that they are arc-polarized. In agreement with earlier results from PSP’s first encounter, we find that groups of longer switchbacks tend to deflect in the same direction for several hours. However, in contrast to earlier studies, we find that there is no unique direction for these deflections, although several solar encounters showed a non-uniform distribution in deflection direction with a slight preference for the tangential direction. This result suggests a systematic magnetic configuration for switchback generation, which is consistent with interchange reconnection as a source mechanism, although this new evidence does not rule out other mechanisms, such as the expansion of wave modes.