论文标题
重新访问非热线宽度与横向MHD波幅度之间的关系
Revisiting the relation between nonthermal line widths and transverse MHD wave amplitudes
论文作者
论文摘要
太阳电晕中横向MHD波的观测和3D MHD模拟已经确定，真实的波能隐藏在光学薄发射线的非热线宽度中。这表明了非热线宽度和横向波幅度之间的关系，以估计真实波能。在过去的十年中，几项研究假设均方根（RMS）波幅度大于非热线宽度，其宽度为$ \ sqrt {2} $。但是，一些研究在估计RMS波幅度的同时忽略了这一因素。因此，这种关系似乎存在差异。在这项研究中，我们通过构建一个简单的数学模型，然后进行3D MHD模拟来研究非热线宽度对波幅度的依赖性。我们得出了线性极化，圆形极化振荡的关系，以及多个速度驱动器激发的振荡。我们注意到数学模型和数值模拟之间的匹配非常好。我们得出的结论是，RMS波幅度永远不超过非热线宽度，这引起了关于较早的研究声称横波具有足够能量以加热太阳能电晕的问题。
Observations and 3D MHD simulations of the transverse MHD waves in the solar corona have established that true wave energies hide in the nonthermal line widths of the optically thin emission lines. This displays the need for a relation between the nonthermal line widths and transverse wave amplitudes for estimating the true wave energies. In the past decade, several studies have assumed that the root mean square (rms) wave amplitudes are larger than nonthermal line widths by a factor of $\sqrt{2}$. However, a few studies have ignored this factor while estimating rms wave amplitudes. Thus there appears to exist a discrepancy in this relation. In this study, we investigate the dependence of nonthermal line widths on wave amplitudes by constructing a simple mathematical model followed by 3D MHD simulations. We derive this relation for the linearly polarised, circularly polarised oscillations, and oscillations excited by multiple velocity drivers. We note a fairly good match between mathematical models and numerical simulations. We conclude that the rms wave amplitudes are never greater than the nonthermal line widths which raises questions about earlier studies claiming transverse waves carry enough energy to heat the solar corona.
