A NEW ENTHALPY-BASED APPROACH TO THE TRANSITION REGION IN AN IMPULSIVELY HEATED CORONA
A NEW ENTHALPY-BASED APPROACH TO THE TRANSITION REGION IN AN IMPULSIVELY HEATED CORONA
复制标题
脉冲加热电晕中过渡区域的一种新的基于焓的方法
DOI：
10.1088/2041-8205/710/1/l39
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
P. Cargill
中科院分区：
文献类型：
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作者：
Stephen J. Bradshaw;P. Cargill
对日冕的观测揭示了持续和普遍存在的红移，这对应于大量的下行流。对于脉冲加热的电晕（例如，通过纳米火花），这表明大多数组成环结构处于其生命周期的辐射冷却阶段，并且这些运动不应用于验证任何提出的加热理论的预测。然而，大量的向下流动的性质提出了这样的可能性，即焓可能在回路的能量平衡中起关键作用，特别是它为过渡区辐射提供动力。在这封信中，我们使用一维流体动力学模拟环路冷却表明，从日冕的焓损失很容易足以供电的过渡区辐射。这与长期以来的观点形成对比，即向下的热传导为过渡区提供动力。过渡区和日冕之间的传统区别仅在温度方面是一个严重的非物理简化，这些大气层之间的界面的正确定义需要详细了解它们的能量平衡。为此，我们提出了一个强大的新定义的过渡区。
Observations of the solar corona reveal persistent and ubiquitous redshifts, which correspond to bulk downflows. For an impulsively heated corona (e.g., by nanoflares), this indicates that a majority of the component loop structures are in the radiatively cooling phase of their lifecycle, and these motions should not be used to verify the predictions of any proposed theory of heating. However, the nature of the bulk downflows raises the possibility that enthalpy may play a key role in the energy balance of the loops and in particular that it powers the transition region radiation. In this Letter, we use one-dimensional hydrodynamic simulations of loop cooling to show that enthalpy losses from the corona are easily sufficient to power the transition region radiation. This contrasts with the long-held view that downward thermal conduction powers the transition region. The traditional distinction between the transition region and the corona in terms of temperature alone is then a grossly unphysical simplification, and a proper definition of the interface between these atmospheric layers requires a detailed knowledge of their energy balance. To this end, we propose a robust new definition of the transition region.