Observations of high and low Fe charge states in individual solar wind streams with coronal-hole origin
Observations of high and low Fe charge states in individual solar wind streams with coronal-hole origin
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DOI：
10.1051/0004-6361/201527998
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发表时间：
2016-09
影响因子：
6.5
通讯作者：
V. Heidrich-Meisner;T. Peleikis;M. Kruse;L. Berger;R. Wimmer–Schweingruber
中科院分区：
文献类型：
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作者：
V. Heidrich-Meisner;T. Peleikis;M. Kruse;L. Berger;R. Wimmer–Schweingruber
上下文。起源于冕洞的太阳风相对较好地被理解，与所谓的慢太阳风相比，它的特征是密度和平均电荷状态较低。除波动扰动外，日冕洞太阳风的平均性质是基本不变的。目标。在这个案例研究中，我们集中在日冕洞太阳风流的高级成分探测器(ACE)上的太阳风离子组成能谱仪(SWICS)上的观测，结果表明，尽管日冕洞太阳风中的O和C电荷态很低，但Fe电荷分布的变化更大。特别地，我们说明了日冕洞太阳风中的铁电荷态常常与慢太阳风中的铁电荷态一样高。方法：研究方法。我们根据日冕-黑洞太阳风流的碰撞年龄以及它们各自的O和C电荷状态选择了单个的日冕-黑洞太阳风流，并分析了它们的Fe电荷态分布。此外，结合简单的弹道反映射和势场源面模型，具有高和低Fe电荷状态的流之间的跃迁被映射回光球层。比较了2004年和2006年高铁和低铁电荷态流的相对频率。结果。我们发现了几个典型的日冕空穴流，它们的铁电荷态与慢太阳风中的铁电荷态一样高或更低。2006年的八次这样的过渡被映射回赤道冕洞，这些洞要么是孤立的，要么与北部的冕洞相连。到目前为止，识别与转变相关的冠状结构的尝试还没有定论。
Context. The solar wind originating from coronal holes is comparatively well-understood and is characterized by lower densities and average charge states compared to the so-called slow solar wind. Except for wave perturbations, the average properties of the coronal-hole solar wind are passably constant. Aims. In this case study, we focus on observations of the Solar Wind Ion Composition Spectrometer (SWICS) on the Advanced Composition Explorer (ACE) of individual streams of coronal-hole solar wind that illustrate that although the O and C charge states are low in coronal-hole wind, the Fe charge distribution is more variable. In particular, we illustrate that the Fe charge states in coronal-hole solar wind are frequently as high as in slow solar wind. Methods. We selected individual coronal-hole solar wind streams based on their collisional age as well as their respective O and C charge states and analyzed their Fe charge-state distributions. Additionally, with a combination of simple ballistic back-mapping and the potential field source surface model, transitions between streams with high and low Fe charge states were mapped back to the photosphere. The relative frequency of high and low Fe charge-state streams is compared for the years 2004 and 2006. Results. We found several otherwise typical coronal-hole streams that include Fe charge states either as high as or lower than in slow solar wind. Eight such transitions in 2006 were mapped back to equatorial coronal holes that were either isolated or connected to the northern coronal-hole. Attempts to identify coronal structures associated with the transitions were so far inconclusive.