论文标题

2019年7月2日的太阳最低日食:ii。 Fe X,XI和XIV的第一个绝对亮度测量和MHD模型预测至3.4 rs

The Solar Minimum Eclipse of 2019 July 2: II. The First Absolute Brightness Measurements and MHD Model Predictions of Fe X, XI and XIV out to 3.4 Rs

论文作者

Boe, Benjamin, Habbal, Shadia, Downs, Cooper, Druckmüller, Miloslav

论文摘要

我们介绍了Fe X,Fe XI和Fe XIV可见的冠状发射线的空间解决绝对亮度,从1.08到3.4 $ R_ \ odot $,在2019年7月2日在7月2日的太阳日食(TSE)期间观察到。电晕的形态是太阳最小值的典型代表,其偶极场优势由大的极性冠状孔和宽阔的赤道式流式带。发现Fe XI线是最亮的,其次是Fe X和Fe XIV(在磁盘$ b_ \ odot $单位中)。所有线条在彩带和冠状孔之间均具有亮度变化,其中Fe XIV表现出最大的变化。但是,Fe X与纬度保持出人意料的均匀。 FE线亮度用于推断整个电晕的相对离子丰度和视线平均电子温度($ T_E $),在冠状核心的冠状孔中产生1.25-1.4 mk的冠状孔中的值。然后,与该TSE的PSI磁性水力动力学模型预测相比,线亮度和推断的$ t_e $值进行了数量的定量。 MHD模型一般来说,MHD模型预测了FE线,而正向建模的线比略微低估了在整个Corona上观察到的$ T_E $在5至10%之内的观察性$ T_E $。极性冠状孔中的较大差异可能表明该方法中的加热和/或其他局限性不足。这些比较强调了TSE观测对于约束电晕和太阳风形成模型的重要性。

We present the spatially resolved absolute brightness of the Fe X, Fe XI and Fe XIV visible coronal emission lines from 1.08 to 3.4 $R_\odot$, observed during the 2019 July 2 total solar eclipse (TSE). The morphology of the corona was typical of solar minimum, with a dipole field dominance showcased by large polar coronal holes and a broad equatorial streamer belt. The Fe XI line is found to be the brightest, followed by Fe X and Fe XIV (in disk $B_\odot$ units). All lines had brightness variations between streamers and coronal holes, where Fe XIV exhibited the largest variation. However, Fe X remained surprisingly uniform with latitude. The Fe line brightnesses are used to infer the relative ionic abundances and line of sight averaged electron temperature ($T_e$) throughout the corona, yielding values from 1.25 - 1.4 MK in coronal holes up to 1.65 MK in the core of streamers. The line brightnesses and inferred $T_e$ values are then quantitatively compared to the PSI Magnetohydrodynamic model prediction for this TSE. The MHD model predicted the Fe lines rather well in general, while the forward modeled line ratios slightly underestimated the observationally inferred $T_e$ within 5 to 10 % averaged over the entire corona. Larger discrepancies in the polar coronal holes may point to insufficient heating and/or other limitations in the approach. These comparisons highlight the importance of TSE observations for constraining models of the corona and solar wind formation.

扫码加入交流群

加入微信交流群

微信交流群二维码

扫码加入学术交流群,获取更多资源