Study of the polarization produced by the Zeeman effect in the solar Mg?i?b lines
Study of the polarization produced by the Zeeman effect in the solar Mg?i?b lines
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太阳Mg?i?b线中塞曼效应产生的偏振研究
DOI：
10.1093/mnras/sty2685
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发表时间：
2018
影响因子：
4.8
通讯作者：
Suematsu Y
中科院分区：
文献类型：
--
作者：
Quintero?Noda C;Uitenbroek H;Carlsson M;Orozco?Su?rez D;Katsukawa Y;Shimizu T;Ruiz?Cobo B;Kubo M;Oba T;Kawabata Y;Hasegawa T;Ichimoto K;Anan T;Suematsu Y
下一代太阳观测站的目标是了解太阳色球层的磁性。因此，了解色球光谱线的偏振特征是至关重要的。为此，我们在这里分别在5183.6,5172.7和5167.3 Å检查三个Fraunhofer Mgib1，b2和b4系的适用性。我们首先描述了一个简化的原子模型，该模型只有6个能级和3个线跃迁，用于计算涉及到mgiline跃迁的3p-4s（多重数2）能级的原子居群，假设非局部热力学条件，并使用无场近似只考虑塞曼效应。我们将这个简化的原子与更复杂的原子进行了测试，发现尽管计算的轮廓存在差异，但与简单原子在速度和鲁棒性方面提供的优势相比，它们是很小的。通过对三种线的比较，我们得出结论：b2线在相似的高度形成，并且总是显示较弱的偏振信号，而eb4与光球线严重混合。我们还将mgib2与kid1和Caii8542 Å谱线进行了比较，发现前者对位于后两条谱线所覆盖高度之间的大气参数非常敏感。这使得mgib2成为未来多线观测的绝佳候选者，这些观测旨在无缝地推断太阳低层大气中不同特征的热和磁性。
The next generation of solar observatories aim to understand the magnetism of the solar chromosphere. Therefore, it is crucial to understand the polarimetric signatures of chromospheric spectral lines. For this purpose, we here examine the suitability of the three Fraunhofer Mgib1,b2, andb4lines at 5183.6, 5172.7, and 5167.3 Å, respectively. We start by describing a simplified atomic model of only six levels and three line transitions for computing the atomic populations of the 3p-4s (multiplet number 2) levels involved in the Mgibline transitions assuming non-local thermodynamic conditions and considering only the Zeeman effect using the field-free approximation. We test this simplified atom against more complex ones finding that, although there are differences in the computed profiles, they are small compared with the advantages provided by the simple atom in terms of speed and robustness. After comparing the three Mgilines, we conclude that the most capable one is theb2line asb1forms at similar heights and always shows weaker polarization signals, whileb4is severely blended with photospheric lines. We also compare Mgib2with the KiD1and Caii8542 Å lines finding that the former is sensitive to the atmospheric parameters at heights that are in between those covered by the latter two lines. This makes Mgib2an excellent candidate for future multiline observations that aim to seamlessly infer the thermal and magnetic properties of different features in the lower solar atmosphere.