The S-Web Origin of Composition Enhancement in the Slow-to-moderate Speed Solar Wind

Connecting the solar wind observed throughout the heliosphere to its origins in the solar corona is one of the central aims of heliophysics. The variability in the magnetic field, bulk plasma, and heavy ion composition properties of the slow wind are thought to result from magnetic reconnection processes in the solar corona. We identify regions of enhanced variability and composition in the solar wind from 2003 April 15 to May 13 (Carrington Rotation 2002), observed by the Wind and Advanced Composition Explorer spacecraft, and demonstrate their relationship to the separatrix–web (hereafter, S-Web) structures describing the corona’s large-scale magnetic topology. There are four pseudostreamer (PS) wind intervals and two helmet streamer (HS) heliospheric current sheet/plasma sheet crossings (and an interplanetary coronal mass ejection), which all exhibit enhanced alpha-to-proton ratios and/or elevated ionic charge states of carbon, oxygen, and iron. We apply the magnetic helicity–partial variance of increments (H m –PVI) procedure to identify coherent magnetic structures and quantify their properties during each interval. The mean duration of these structures are ∼1 hr in both the HS and PS wind. We find a modest enhancement above the power-law fit to the PVI waiting-time distribution in the HS-associated wind at the 1.5–2 hr timescales that is absent from the PS intervals. We discuss our results in the context of previous observations of the ∼90 minutes periodic density structures in the slow solar wind, further development of the dynamic S-Web model, and future Parker Solar Probe and Solar Orbiter joint observational campaigns.

将在整个日球层中观测到的太阳风与其在太阳日冕中的起源联系起来是太阳物理学的核心目标之一。慢太阳风的磁场、体等离子体以及重离子组成特性的变化被认为是由太阳日冕中的磁重联过程导致的。我们确定了2003年4月15日至5月13日（卡林顿自转周2002）期间太阳风中变化性和组成增强的区域，这些区域是由“风”号和“先进成分探测器”航天器观测到的，并展示了它们与描述日冕大尺度磁拓扑结构的分界面 - 网络（以下简称S - Web）结构的关系。有四个伪冕流（PS）风区间和两个盔状冕流（HS）日球层电流片/等离子体片穿越（以及一次行星际日冕物质抛射），它们都表现出增强的α粒子与质子比率和/或碳、氧和铁的离子电荷态升高。我们应用磁螺旋度 - 增量部分方差（Hm - PVI）方法来识别相干磁结构，并在每个区间量化它们的特性。在HS风和PS风中，这些结构的平均持续时间约为1小时。我们发现，在1.5 - 2小时的时间尺度上，与HS相关的风中，PVI等待时间分布的幂律拟合之上有适度的增强，而在PS区间中则没有这种情况。我们在先前对慢太阳风中约90分钟周期性密度结构的观测、动态S - Web模型的进一步发展以及未来“帕克太阳探测器”和“太阳轨道器”联合观测活动的背景下讨论我们的结果。