Spectral Characteristics and Formation Height of Off-limb Flare Ribbons
Spectral Characteristics and Formation Height of Off-limb Flare Ribbons
复制标题
离臂耀斑带的光谱特征和形成高度
DOI：
10.3847/1538-4357/ab9603
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
J. Allred
中科院分区：
文献类型：
--
作者：
D. Kuridze;M. Mathioudakis;P. Heinzel;J. Koza;H. Morgan;R. Oliver;A. Kowalski;J. Allred
耀斑带是低太阳大气中耀斑能量耗散的明亮表现。我们首次报道了位于Hβ和CaII8542ä谱线边缘附近的耀斑带的高分辨率成像光谱观测，并与辐射流体动力学模拟进行了详细的比较。瑞典太阳望远镜对X8.2级太阳耀斑SOL2017-09-10T16：06 UT的观测显示，位于耀斑环足点附近的Hβ线翼图像中有明亮的水平发射层。在Hβ翼观察到的带状物与标称的光球翼之间的视距约为300-500千米。CA II 8542ä线翼图像显示，位于肢体边缘的带状发射要微弱得多，与肢体没有明显的分离。用RADYN模式研究了耀斑大气的合成谱线廓线，与观测结果吻合较好。模拟表明，对于视线相对于垂直方向基本上倾斜的边缘，耀斑大气模式再现了边缘外Hβ带的高对比度及其在光球层上方的显著高度。CA II 8542á线翼图像中的条带位于较低的太阳大气深处，对比度较低。对电子束能量高度沉积和强度贡献函数的比较表明，Hβ线翼强度可以作为低太阳大气耀斑能量沉积的有效示踪剂。
Flare ribbons are bright manifestations of flare energy dissipation in the lower solar atmosphere. For the first time, we report on high-resolution imaging spectroscopy observations of flare ribbons situated off limb in the Hβ and Ca ii 8542 Å lines and make a detailed comparison with radiative hydrodynamic simulations. Observations of the X8.2 class solar flare SOL 2017-09-10T16:06 UT obtained with the Swedish Solar Telescope reveal bright horizontal emission layers in Hβ line-wing images located near the footpoints of the flare loops. The apparent separation between the ribbon observed in the Hβ wing and the nominal photospheric limb is about 300–500 km. The Ca ii 8542 Å line-wing images show much fainter ribbon emissions located right on the edge of the limb, without clear separation from the limb. RADYN models are used to investigate synthetic spectral line profiles for the flaring atmosphere, and good agreement is found with the observations. The simulations show that, toward the limb, where the line of sight is substantially oblique with respect to the vertical direction, the flaring atmosphere model reproduces the high contrast of the off-limb Hβ ribbons and their significant elevation above the photosphere. The ribbons in the Ca ii 8542 Å line-wing images are located deeper in the lower solar atmosphere with a lower contrast. A comparison of the height deposition of electron beam energy and the intensity contribution function shows that the Hβ line-wing intensities can be a useful tracer of flare energy deposition in the lower solar atmosphere.
DOI：
10.3847/0004-637x/827/2/101
发表时间：
2016-05
期刊：
The Astrophysical Journal
影响因子：
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作者：
G. Kerr;L. Fletcher;A. Russell;J. Allred
通讯作者：
G. Kerr;L. Fletcher;A. Russell;J. Allred