Investigating the Cross Sections of Coronal Mass Ejections through the Study of Nonradial Flows with STEREO/PLASTIC
Investigating the Cross Sections of Coronal Mass Ejections through the Study of Nonradial Flows with STEREO/PLASTIC
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DOI：
10.3847/1538-4357/ac32e1
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发表时间：
2021-10
期刊：
影响因子：
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通讯作者：
N. Al-Haddad;A. Galvin;N. Lugaz;C. Farrugia;Wenyuan Yu
中科院分区：
文献类型：
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作者：
N. Al-Haddad;A. Galvin;N. Lugaz;C. Farrugia;Wenyuan Yu
太阳风，当测量接近1 Au，被发现主要是径向向外流动。然而，在东西和南北两个方向上，气流与径向方向的夹角都达到15°。气流相互作用区是造成东西向气流偏转的一个常见原因。日冕物质抛射（CME）可能至少以两种不同的方式与非径向流相关联：（1）在鞘层区域，特别是靠近磁性抛射物前缘边界的太阳风的偏转，可能导致大的非径向流;（2）磁性抛射物的膨胀可能包括非径向分量，当抛射物远离其中心轴时，应该很容易测量。在这项工作中，我们首先提出了一般的统计数据的非径向太阳风流动的STEREO/PLASTIC测量的整个前13年的使命，专注于太阳周期的变化。然后，我们专注于较大的偏转气流角，并确定其中大部分与太阳极小期附近的SIR和太阳极大期附近的CME有关。然而，我们没有发现明显的证据，强烈偏转的流量，将预期如果大偏转周围的磁性喷出物或喷出物与椭圆形横截面与大偏心率是常见的。我们使用这些结果来更好地了解CME膨胀和磁性喷出物的性质，并指出我们对CME理解的不足之处。
The solar wind, when measured close to 1 au, is found to flow mostly radially outward. There are, however, periods when the flow makes angles up to 15° away from the radial direction, both in the east–west and north–south directions. Stream interaction regions (SIRs) are a common cause of east–west flow deflections. Coronal mass ejections (CMEs) may be associated with nonradial flows in at least two different ways: (1) the deflection of the solar wind in the sheath region, especially close to the magnetic ejecta front boundary, may result in large nonradial flows; and (2) the expansion of the magnetic ejecta may include a nonradial component, which should be easily measured when the ejecta is crossed away from its central axis. In this work, we first present general statistics of nonradial solar wind flows as measured by STEREO/PLASTIC throughout the first 13 yr of the mission, focusing on solar cycle variation. We then focus on the larger deflection flow angles and determine that most of these are associated with SIRs near solar minimum and with CMEs near solar maximum. However, we find no clear evidence of strongly deflected flows, as would be expected if large deflections around the magnetic ejecta or ejecta with elliptical cross sections with large eccentricities were common. We use these results to develop a better understanding of CME expansion and the nature of magnetic ejecta, and point to shortcomings in our understanding of CMEs.