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arXiv 0805.1602astro-ph
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从Hinode/SOT看quiet-Sun拓扑

A new view of quiet-Sun topology from Hinode/SOT

S. Regnier, C. E. Parnell, A. L. Haynes

摘要:

随着最近Hinode卫星的发射,我们对安静太阳区域的性质和演变的看法有所改善。根据新的高分辨率观测结果,我们重新研究了安静太阳的拓扑性质。拓扑学是解释磁场的复杂性、重联过程的发生和日冕的加热的工具。这封信旨在为这些不同的主题提供新的见解。利用高分辨率的Hinode/SOT观测光球上的视线磁场,我们计算了假设有位场的上述区域的三维磁场。从三维场出发,我们确定了磁位形中零点的存在性。从这个模型的一个连续的领域,我们发现,空点的分布与高度是显着不同的,在以前的研究报告。特别是,零点主要位于底部边界层以上的光球层(54%)和色球层(44%),只有少数零点在日冕(2%)。在太阳大气中的零点密度(表示为零点数量与光球磁性碎片数量的比率)估计在3%至8%之间,这取决于用于确定所观测光球中磁性碎片数量的方法。这项研究表明,日冕加热的磁重联在日冕零点是不可能的。我们的研究结果并不排除在其他拓扑特征的日冕加热。我们还报告了色球的拓扑复杂性,强烈建议最近的观测从Hinode/SOT。

英文摘要:

With the recent launch of the Hinode satellite our view of the nature and evolution of quiet-Sun regions has been improved. In light of the new high resolution observations, we revisit the study of the quiet Sun's topological nature. Topology is a tool to explain the complexity of the magnetic field, the occurrence of reconnection processes, and the heating of the corona. This Letter aims to give new insights to these different topics. Using a high-resolution Hinode/SOT observation of the line-of-sight magnetic field on the photosphere, we calculate the three dimensional magnetic field in the region above assuming a potential field. From the 3D field, we determine the existence of null points in the magnetic configuration. From this model of a continuous field, we find that the distribution of null points with height is significantly different from that reported in previous studies. In particular, the null points are mainly located above the bottom boundary layer in the photosphere (54%) and in the chromosphere (44%) with only a few null points in the corona (2%). The density of null points (expressed as the ratio of the number of null points to the number of photospheric magnetic fragments) in the solar atmosphere is estimated to be between 3% and 8% depending on the method used to identify the number of magnetic fragments in the observed photosphere. This study reveals that the heating of the corona by magnetic reconnection at coronal null points is unlikely. Our findings do not rule out the heating of the corona at other topological features. We also report the topological complexity of the chromosphere as strongly suggested by recent observations from Hinode/SOT.

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