论文标题
极性太阳能电晕的Fe XII和Fe XIII线宽度高达1.5 rsun
Fe XII and Fe XIII Line Widths in the Polar Off-limb Solar Corona up to 1.5 Rsun
论文作者
论文摘要
在太阳能电晕中形成的光谱线的非热宽度通常用于寻求在电晕中传播的Alfvén波的证据。为了更好地了解不同高度处的线路宽度的变化，我们测量了强fe \ textsc {xii} 192.4、193.5和195.1 \mboxå和fe \ fe \ textsc {xiii} 202.02.0 \mboxå中的线路的宽度\ $ $ $ $ $。 （EIS）在\ textit {hinode}卫星上。我们将我们的测量结果与Alfvén波太阳模型（AWSOM）和频谱模块的预测进行了比较。我们发现，fe \ textsc {xii}和fe \ textsc {xiii}线宽度首先单调地以1.1 $ r_ \ odot $单打增加，然后继续在1.1和1.1和1.5 $ r_ \ odot $之间波动。 fe \ textsc {xii}和fe \ textsc {xiii}的合成线宽度以下1.3 $ r_ \ odot $明显低于观察到的。我们发现，视线中的流媒体发射的发射显着污染了冠状孔线轮廓，即使在观测和模拟中，甚至最高可达1.5 $ r_ \ odot $。我们建议，观测值和模拟之间的差异是由于AWSOM模拟中流媒体的非热宽片不足引起的，或者观察值受到流媒体的影响较小。我们的结果强调了鉴定在LIMB观察中鉴定冠状EUV排放的起源的重要性。
The nonthermal broadening of spectral lines formed in the solar corona is often used to seek the evidence of Alfvén waves propagating in the corona. To have a better understanding of the variation of line widths at different altitudes, we measured the line widths of the strong Fe \textsc{xii} 192.4, 193.5, and 195.1 \mboxÅ and Fe \textsc{xiii} 202.0 \mboxÅ in an off-limb southern coronal hole up to 1.5 $R_\odot$ observed by the Extreme Ultraviolet Spectrometer (EIS) on board the \textit{Hinode} satellite. We compared our measurements to the predictions from the Alfvén Wave Solar Model (AWSoM) and the SPECTRUM module. We found that the Fe \textsc{xii} and Fe \textsc{xiii} line widths first increase monotonically below 1.1 $R_\odot$, and then keep fluctuating between 1.1 and 1.5 $R_\odot$. The synthetic line widths of Fe \textsc{xii} and Fe \textsc{xiii} below 1.3 $R_\odot$ are notably lower than the observed ones. We found that the emission from a streamer in the line of sight significantly contaminates the coronal hole line profiles even up to 1.5 $R_\odot$ both in observations and simulations. We suggest that either the discrepancy between the observations and simulations is caused by insufficient nonthermal broadening at the streamer in the AWSoM simulation or the observations are less affected by the streamer. Our results emphasize the importance of identifying the origin of the coronal EUV emission in off-limb observations.
