Coronal Heating through Braiding of Magnetic Field Lines
Coronal Heating through Braiding of Magnetic Field Lines
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DOI：
10.1086/427168
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发表时间：
2004-09
期刊：
影响因子：
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通讯作者：
H. Peter;B. Gudiksen;Å. Nordlund
中科院分区：
文献类型：
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作者：
H. Peter;B. Gudiksen;Å. Nordlund
像我们的太阳这样的冷恒星被一百万度的高温外层大气，日冕所包围。60多年来，将日冕加热到远远超过恒星表面温度的过程的物理性质仍然令人困惑。观测技术和数值模拟的最新进展为解决这一问题打开了新的窗口。我们提出了第一个日冕发射线光谱合成的三维数值模型描述的动态和能量的演变，以及在日冕中的磁场。在这些模型中，日冕通过恒星表面的运动被加热，导致磁场线的编织，感应最终消散的电流。这些前向模型使我们能够合成观测到的属性，如（平均）发射线多普勒频移或排放措施，在外层大气中，这直到现在还没有被理解的理论，即使在过去已经提出了许多建议。由于我们的模型通过了这些观测测试，我们得出结论，通量编织机制是太阳和类太阳恒星磁封闭日冕的主要加热过程的主要候选者。
Cool stars such as our Sun are surrounded by a million degree hot outer atmosphere, the corona. For more than 60 years, the physical nature of the processes heating the corona to temperatures well in excess of those on the stellar surface have remained puzzling. Recent progress in observational techniques and numerical modeling now opens a new window to approach this problem. We present the first coronal emission-line spectra synthesized from three-dimensional numerical models describing the evolution of the dynamics and energetics as well as of the magnetic field in the corona. In these models the corona is heated through motions on the stellar surface that lead to a braiding of magnetic field lines inducing currents that are finally dissipated. These forward models enable us to synthesize observed properties such as (average) emission-line Doppler shifts or emission measures in the outer atmosphere, which until now have not been understood theoretically, even though many suggestions have been made in the past. As our model passes these observational tests, we conclude that the flux braiding mechanism is a prime candidate for being the dominant heating process of the magnetically closed corona of the Sun and solar-like stars.