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arXiv 1602.00787astro-ph.SR
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冕环中振荡慢波的正演模拟及其频率依赖阻尼

Forward Modelling of Propagating Slow Waves in Coronal Loops and Their Frequency-Dependent Damping

Sudip Mandal, Norbert Magyar, Ding Yuan, Tom Van Doorsselaere, Dipankar Banerjee

摘要:

冕环中的振荡慢波表现出一种阻尼,这种阻尼取决于波的频率。在这项研究中,我们的目的是调查的阻尼长度(L $_d$)与传播波的频率的关系。我们提出了一个具有均匀密度和温度的三维日冕环模型,并研究了四个选定的波周期的频率依赖的阻尼机制。我们包括热传导,以阻尼波,因为它们通过环路传播。数值模型输出已被正向模拟,以生成SDO/AIA 171毫米和193毫米通道的合成图像。使用正向建模,将原子发射特性纳入强度图像,使我们能够直接将我们的结果与实际观测结果进行比较。结果表明,阻尼长度与周期呈线性关系。我们还测量的阻尼长度上的排放性能的贡献,通过使用从模拟的密度值。此外,我们还计算了L $_d$与波浪周期的理论关系,并表明这与我们从数值模拟和早期观测中得到的结果是一致的。

英文摘要:

Propagating slow waves in coronal loops exhibit a damping which depends upon the frequency of the waves. In this study we aim to investigate the relationship of the damping length (L$_d$) with the frequency of the propagating wave. We present a 3-D coronal loop model with uniform density and temperature and investigate the frequency dependent damping mechanism for the four chosen wave periods. We include the thermal conduction to damp the waves as they propagate through the loop. The numerical model output has been forward modelled to generate synthetic images of SDO/AIA 171 Å and 193 Å channels. The use of forward modelling, which incorporates the atomic emission properties into the intensity images, allows us to directly compare our results with the real observations. The results show that the damping lengths vary linearly with the periods. We also measure the contributions of the emission properties on the damping lengths by using density values from the simulation. In addition to that} we have also calculated the theoretical dependence of L$_d$ with wave periods and showed that it is consistent with the results we obtained from the numerical modelling and earlier observations.

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