Exploring Plasma Heating in the Current Sheet Region in a Three-dimensional Coronal Mass Ejection Simulation
Exploring Plasma Heating in the Current Sheet Region in a Three-dimensional Coronal Mass Ejection Simulation
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DOI：
10.3847/1538-4357/ab4ce8
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发表时间：
2019-12-10
影响因子：
4.9
通讯作者：
Murphy, Nicholas A.
中科院分区：
文献类型：
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作者：
Reeves, Katharine K.;Torok, Tibor;Murphy, Nicholas A.
我们模拟了日冕物质抛射使用三维磁流体动力学代码，包括日冕加热，热传导和辐射冷却的能量方程。1 R-s处的磁通量分布是由叠加在全球偶极场上的局部次表面偶极产生的，模拟了全球日冕内活动区域的存在。在极性反转线附近施加横向电场以引入横向磁场，然后施加会聚流以形成和破坏通量绳，从而产生喷发。我们研究负责等离子体加热和冷却的喷发过程中，包括热传导，辐射，绝热效应，日冕加热，欧姆加热的量。我们发现，欧姆加热是一个重要的贡献者热的温度在当前片区域的早期爆发，但在后期阶段，绝热压缩在加热等离子体中起着重要的作用。在整个重联过程中，热传导在将热能从电流片区域传输出去方面也起着重要作用，产生了“热晕”并扩大了高温区域。我们模拟发射从太阳望远镜为这次喷发，并发现有证据表明，从上面的耀斑环晚在喷发，绝热加热是占主导地位的加热项加热等离子体发射。这些结果提供了一个解释热超拱廊等离子体片，经常观察到的X射线和极紫外波长在大耀斑的衰变阶段。
We simulate a coronal mass ejection using a three-dimensional magnetohydrodynamic code that includes coronal heating, thermal conduction, and radiative cooling in the energy equation. The magnetic flux distribution at 1 R-s is produced by a localized subsurface dipole superimposed on a global dipole field, mimicking the presence of an active region within the global corona. Transverse electric fields are applied near the polarity inversion line to introduce a transverse magnetic field, followed by the imposition of a converging flow to form and destabilize a flux rope, producing an eruption. We examine the quantities responsible for plasma heating and cooling during the eruption, including thermal conduction, radiation, adiabatic effects, coronal heating, and ohmic heating. We find that ohmic heating is an important contributor to hot temperatures in the current sheet region early in the eruption, but in the late phase, adiabatic compression plays an important role in heating the plasma there. Thermal conduction also plays an important role in the transport of thermal energy away from the current sheet region throughout the reconnection process, producing a "thermal halo" and widening the region of high temperatures. We simulate emission from solar telescopes for this eruption and find that there is evidence for emission from heated plasma above the flare loops late in the eruption, when the adiabatic heating is the dominant heating term. These results provide an explanation for hot supra-arcade plasma sheets that are often observed in X-rays and extreme ultraviolet wavelengths during the decay phase of large flares.