Solar wind from the coronal hole boundaries
Solar wind from the coronal hole boundaries
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来自冕洞边界的太阳风
DOI：
10.1029/2004ja010896
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发表时间：
2005
影响因子：
--
通讯作者：
R. Steiger
中科院分区：
文献类型：
--
作者：
N. Schwadron;D. McComas;H. A. Elliott;G. Gloeckler;J. Geiss;R. Steiger
[1]最近利用现场观测的研究确定，行星际空间中快风和慢风之间的界面有两个不同的部分：一个平滑变化的边界层流动，它位于冕洞快风的侧面，另一个是中等和慢速太阳风之间更尖锐的等离子体不连续性。其他使用现场观测和建模的研究已经证明了日球磁场的亚帕克螺旋结构的存在，在这种结构中，太阳上的脚点运动产生的快风和慢风之间的磁连接使磁力线变形，使它们的横向比帕克螺旋小得多。在这里，我们模拟形成的共转相互作用区域，并通过包括一个冕洞边界层（CHBL）和磁足点运动穿过冕洞边界回到太阳，我们解释了详细的，特征的变化组成和磁场方向观察到行星际空间。我们的模型只使用两个自由参数来实现这一点，所有其他参数都直接来自太阳风观测。通过该模型，我们跟踪观察到的行星际变化回到一个内在的两部分结构的太阳风的太阳源。这两部分是：（1）环绕冕洞的CHBL，它的源性质有一个平滑的过渡，产生了从快速到中速（10600 km s−1）的太阳风;（2）尖锐的冕洞不连续性，将中速和中等温度的太阳风与慢速太阳风分开。这项研究建立了太阳风的速度，电荷态成分，和磁场方向的特征变化之间的连接在5 Au附近的两部分结构的冕洞边界在太阳的来源原位观察。
[1] Recent studies using in situ observations established that the interface between fast and slow wind in interplanetary space has two distinct parts: a smoothly varying boundary layer flow that flanks fast wind from coronal holes and a sharper plasma discontinuity between intermediate and slow solar wind. Other studies using in situ observations and modeling have demonstrated the existence of the sub-Parker spiral structure of the heliospheric magnetic field in which the magnetic connection between fast and slow wind created by foot point motion at the Sun deforms field lines, making them significantly less transverse than the Parker spiral. Here we model the formation of corotating interaction regions, and by including a coronal hole boundary layer (CHBL) and magnetic foot point motion across the coronal hole boundary back at the Sun we explain the detailed, characteristic variations in composition and magnetic field orientation observed in interplanetary space. Our model accomplishes this using only two free parameters, with all other quantities derived directly from solar wind observations. Through the model we trace the observed interplanetary variations back to an intrinsic two-part structure in the source of solar wind at the Sun. These parts are (1) a CHBL that encircles the coronal hole and has a smooth transition in the source properties that produce the fast through intermediate speed (∼600 km s−1) solar wind and (2) a sharp coronal hole discontinuity separating the distinct sources of solar wind with intermediate speeds and temperatures from slow solar wind. This study establishes the connection between the characteristic variations of the solar wind speed, charge state composition, and magnetic field orientation observed in situ near 5 AU with their sources in the two-part structure of coronal hole boundaries back at the Sun.