Scaling of heating rates in solar coronal loops
Scaling of heating rates in solar coronal loops
复制标题
太阳日冕环路加热速率的缩放
作者：
J. Klimchuk;L. Porter
日冕的气体温度高达几百万度，比下面的光球层还要热几个数量级。加热日冕（以及更普遍的太阳型恒星的日冕）的物理过程的本质一直是一个长期存在的谜团。已经提出了一些看似合理的加热机制，但到目前为止，观测还无法区分它们。在这里，我们表明，日冕加热具有标度特性，应该提供一个强大的诊断的基本机制。日冕磁场将日冕等离子体组织成环状特征，形成日冕的基本结构元素2。我们表明，冠状环的压力和长度是统计相关的，这表明加热速率的规模与大约环长度的平方成反比。现有的日冕加热理论对这种标度应该是什么做出了不同的预测，目前看来，由应力日冕磁场引起的能量耗散模型3 -4与我们的观测结果最一致。
THE gas of the solar corona is at a temperature of several million degrees, orders of magnitude hotter than the underlying photosphere. The nature of the physical process that heats the solar corona (and the coronae of solar-type stars more generally) has been a long-standing puzzle. A number of plausible heating mechanisms have been proposed, but observations have so far been unable to discriminate between them1. Here we show that coronal heating exhibits scaling properties that should provide a powerful diagnostic of the underlying mechanism. The coronal magnetic field organizes the coronal plasma into loop-like features, which form the basic structural elements of the corona2. We demonstrate that the pressures and lengths of the coronal loops are statistically related, suggesting that the heating rate scales inversely with approximately the square of the loop length. Existing coronal heating theories make different predictions about what this scaling should be, and a model3–4 of energy dissipation by stressed coronal magnetic fields appears at present to be the most consistent with our observational result.