Thermal conduction effects on the kink instability in coronal loops
Thermal conduction effects on the kink instability in coronal loops
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DOI：
10.1051/0004-6361/201015534
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发表时间：
2011-01-01
影响因子：
6.5
通讯作者：
Hood, A. W.
中科院分区：
文献类型：
--
作者：
Botha, G. J. J.;Arber, T. D.;Hood, A. W.
上下文。纳米耀斑对日冕的加热可能是扭结不稳定性的非线性阶段的结果（Hood et al. 2009）。纳米耀斑是一种小的瞬态事件，其中存储的磁能被磁重联耗散。由于这些重联事件所达到的高温，热传导在扭结不稳定性的演变中是不可忽视的。研究热传导对日冕环扭结不稳定性非线性演化的影响。在扭结不稳定和环的长时间演化过程中，评估环的加热效率和热传导作用。数值求解三维非线性磁流体动力学方程，模拟初始处于不稳定平衡状态的日冕环的演化过程。初始状态净电流为零。比较了有热传导和无热传导时回路的时间演化。沿着磁力线的热传导降低了局部温度。这导致温度比在没有导热性的情况下获得的温度低一个数量级。因此，不同的光谱线被激活是否包含热传导，这对观测日冕环有影响。传导过程在快速磁流体动力学现象的时间尺度上也很重要。它减少了一个数量级的动能。结论。热传导在日冕环的扭结不稳定性中起着至关重要的作用，在日冕环的正演模拟中不可忽视。
Context. Heating of the solar corona by nanoflares, which are small transient events in which stored magnetic energy is dissipated by magnetic reconnection, may occur as the result of the nonlinear phase of the kink instability (Hood et al. 2009). Because of the high temperatures reached through these reconnection events, thermal conduction cannot be ignored in the evolution of the kink instability.Aims. To study the effect of thermal conduction on the nonlinear evolution of the kink instability of a coronal loop. To assess the efficiency of loop heating and the role of thermal conduction, both during the kink instability and for the long time evolution of the loop.Methods. Numerically solve the 3D nonlinear magnetohydrodynamic equations to simulate the evolution of a coronal loop that is initially in an unstable equilibrium. The initial state has zero net current. A comparison is made of the time evolution of the loop with thermal conduction and without thermal conduction.Results. Thermal conduction along magnetic field lines reduces the local temperature. This leads to temperatures that are an order of magnitude lower than those obtained in the absence of thermal conductivity. Consequently, different spectral lines are activated with and without the inclusion of thermal conduction, which have consequences for observations of solar corona loops. The conduction process is also important on the timescale of the fast magnetohydrodynamic phenomena. It reduces the kinetic energy released by an order of magnitude.Conclusions. Thermal conduction plays an essential role in the kink instability of coronal loops and cannot be ignored in the forward modelling of such loops.