原子模型对散射偏振理论轮廓的影响

发布时间：2018-05-12 01:30

本文选题：太阳 + 磁场　；参考：《天文学报》2014年05期

【摘要】：太阳磁场的诊断是太阳物理研究中非常重要的一部分.斯托克斯参量I、Q、U和V可以用来完整描述偏振光的信息,对观测得到的斯托克斯光谱进行反演可以诊断太阳磁场的信息.近几十年来,塞曼效应成为磁场诊断的主要手段,利用塞曼效应使谱线产生的分裂可以诊断强度达到几百高斯的强磁场,但是在太阳宁静区中存在大量强度小于100 Gs的弱磁场,对于弱磁场可以利用汉勒效应来诊断,应用汉勒效应诊断弱磁场一直是磁场诊断的主要内容之一,需要对偏振的产生机制有更完整的理解.文章的主要内容是研究在采用不同原子模型的假设下,由散射产生的谱线轮廓的区别,以及在存在磁场时,不同原子模型谱线的汉勒效应的区别.以中性镁为研究对象,选取了7能级、4能级和2能级原子模型,分别研究了这几个原子模型对散射偏振和汉勒效应的影响.发现2能级原子模型和多能级(7能级和4能级)原子模型产生的谱线的偏振度有很大的区别,并且在2能级原子模型假设下b_4线不存在下能级的汉勒效应,但是在多能级的原子模型下b_4线仍存在下能级的汉勒效应.对比7能级原子模型和4能级原子模型,谱线的偏振度只有很小的变化,汉勒效应的表现也基本相同.主要结论如下:在利用中性镁b 3线的线偏振轮廓Q/I反演磁场时,至少需要采用4个能级的原子模型.这主要依赖于谱线形成区域的原子的能级分布,原子能级占有数多的能级在研究中是必须考虑的.
[Abstract]:The diagnosis of solar magnetic field is a very important part of the study of solar physics. The Stokes parameters I _ (Q) _ (U) and V can be used to describe the information of polarized light completely, and the information of the solar magnetic field can be diagnosed by inversion of the observed Stokes spectrum. In recent decades, Zeeman effect has become the main method of magnetic field diagnosis. The splitting of spectral lines produced by Zeeman effect can diagnose a strong magnetic field with a intensity of several hundred Gao Si, but a large number of weak magnetic fields with intensity less than 100Gs exist in the quiet region of the sun. The weak magnetic field can be diagnosed by using the Hanler effect, which is always one of the main contents of magnetic field diagnosis. It is necessary to have a more complete understanding of the mechanism of polarization. The main content of this paper is to study the difference of spectral line profile generated by scattering under the assumption of different atomic models and the difference of Hansel effect of different atomic model lines in the presence of magnetic field. Taking neutral magnesium as the research object, the influence of these atomic models on scattering polarization and Hansel effect is studied by selecting 7 energy level 4 level and 2 level atomic model. It is found that the polarization degree of the spectral lines generated by the two-level atom model is quite different from that generated by the multi-level atomic model, and the Hanler effect of the lower energy level does not exist in the b4 line under the assumption of the two-level atomic model. However, under the multi-level atomic model, the Hanler effect of the lower energy level still exists in the bStud _ 4 line. Compared with the 7-level atomic model and the 4-level atomic model, the polarization degree of the spectral line has only a small change, and the Hamler effect is basically the same. The main conclusions are as follows: when using the linear polarization profile Q / I of neutral Mgb3 line to retrieve the magnetic field, at least four energy level atomic models should be used. This mainly depends on the energy level distribution of atoms in the region of spectral line formation, and the energy level with more atomic energy level must be considered in the study.
【作者单位】：中国科学院云南天文台;中国科学院大学;
【基金】：国家自然科学基金项目(11078005,11373065) 973项目(G2011CB811400)资助
【分类号】：P182.7

【共引文献】