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外文期刊>The Astrophysical journal
>COMBINED MODELING OF ACCELERATION, TRANSPORT, AND HYDRODYNAMIC RESPONSE IN SOLAR FLARES. II. INCLUSION OF RADIATIVE TRANSFER WITH RADYN
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COMBINED MODELING OF ACCELERATION, TRANSPORT, AND HYDRODYNAMIC RESPONSE IN SOLAR FLARES. II. INCLUSION OF RADIATIVE TRANSFER WITH RADYN
Solar flares involve complex processes that are coupled and span a wide range of temporal, spatial, and energy scales. Modeling such processes self-consistently has been a challenge in the past. Here we present results from simulations that couple particle kinetics with hydrodynamics (HD) of the atmospheric plasma. We combine the Stanford unified Fokker–Planck code?that models particle acceleration and transport with the RADYN HD code that models the atmospheric response to collisional heating by accelerated electrons through detailed radiative transfer calculations. We perform simulations using two different electron spectra, one an ad hoc power law and the other predicted by the model of stochastic acceleration by turbulence or plasma waves. Surprisingly, the later model, even with energy flux , can cause "explosive" chromospheric evaporation and drive stronger up- and downflows (and HD shocks). This is partly because our acceleration model, like many others, produces a spectrum consisting of a quasi-thermal component plus a power-law tail. We synthesize emission-line profiles covering different heights in the lower atmosphere, including Hα 6563??, He ii 304??, Ca ii K 3934??, and Si iv 1393??. One interesting result is the unusual high temperature (up to a few times 105 K) of the formation site of He ii 304??, which is expected owing to photoionization-recombination under flare conditions, compared to those in the quiet Sun dominated by collisional excitation. When compared with observations, our results can constrain the properties of nonthermal electrons and thus the poorly understood particle acceleration mechanism.
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机译：太阳耀斑涉及复杂的过程，这些过程相互关联并跨越了很大的时间，空间和能量尺度。在过去，自洽地对此类过程进行建模一直是一个挑战。在这里，我们介绍了将粒子动力学与大气等离子体的流体动力学（HD）耦合的模拟结果。我们将通过Stanford统一的Fokker-Planck代码（用于模拟粒子加速和传输）与RADYN HD代码（通过详细的辐射传递计算来模拟大气对加速电子对碰撞加热的响应）相结合。我们使用两种不同的电子光谱进行仿真，一种是临时功率定律，另一种是通过湍流或等离子波的随机加速度模型预测的。令人惊讶的是，即使具有能量通量，后面的模型也可能导致“爆炸性”的色球蒸发，并导致更强的上，下流（和高清震荡）。这部分是因为我们的加速模型与许多其他模型一样，产生了一个由准热分量和幂律尾部组成的频谱。我们合成了在低层大气中覆盖不同高度的发射线剖面，包括Hα6563′，He 304′′，Ca ii K 3934′和Si iv 1393′。一个有趣的结果是He ii 304 ??形成部位的异常高温（高达105 K的几倍），这是由于在耀斑条件下的光电离复合导致的，相比于在碰撞条件下处于安静的阳光下，He ii 304？励磁。当与观察结果进行比较时，我们的结果可能会限制非热电子的性质，从而限制人们对粒子加速机制的了解。
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