论文标题
由于编织引起的太阳冠状环的湍流而引起的非热线扩展
Non-thermal line broadening due to braiding-induced turbulence in solar coronal loops
论文作者
论文摘要
目的：来自太阳能冠状环的发射线曲线表现出目前模型无法解释的特性。我们研究了与磁场线编织引起的冠状环中血浆加热相关的非热宽。方法：我们通过最初编织磁场的湍流衰变的3D磁流失动力模型来描述冠状环。由此，我们合成了193埃埃XII线，形成约1.5 mk。结果：在合成的光谱中重现了当前对电晕极端紫外线线的关键特征：（i）典型的非热宽度范围为15至20 km/s。 （ii）宽度大致与视场的大小无关。 （iii）线强度与非热宽之间存在相关性。 （iv）发现光谱是非高斯的，在10-20％的翅膀的机翼中具有增强的功率。结论：我们的模型提供了一种解释，即自兼容将加热过程与观察到的非热线扩展联系起来。光谱的非高斯性质是基础速度波动的非高斯性质的结果，被解释为湍流间歇性的标志。
Aims: Emission line profiles from solar coronal loops exhibit properties that are unexplained by current models. We investigate the non-thermal broadening associated with plasma heating in coronal loops that is induced by magnetic field line braiding. Methods: We describe the coronal loop by a 3D magnetohydrodynamic model of the turbulent decay of an initially-braided magnetic field. From this we synthesize the Fe XII line at 193 Angstroms that forms around 1.5 MK. Results: Key features of current observations of extreme UV lines from the corona are reproduced in the synthesised spectra: (i) Typical non-thermal widths range from 15 to 20 km/s. (ii) The widths are approximately independent of the size of the field of view. (iii) There is a correlation between line intensity and the non-thermal broadening. (iv) Spectra are found to be non-Gaussian, with enhanced power in the wings of order 10-20%. Conclusions: Our model provides an explanation that self-consistently connects the heating process to the observed non-thermal line broadening. The non-Gaussian nature of the spectra is a consequence of the non-Gaussian nature of the underlying velocity fluctuations, interpreted as a signature of intermittency in the turbulence.
