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arXiv 2007.08226astro-ph.SR
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主方程理论在弱辐射场极限下极化辐射重分布中的应用。VI。Na I D1和D2谱线在太阳第二光谱中的应用:收敛

Master equation theory applied to the redistribution of polarized radiation in the weak radiation field limit. VI. Application to the Second Solar Spectrum of the Na I D1 & D2 lines: convergence

V. Bommier

摘要:

本文提出了一个数值应用的自洽理论的部分重新分配在非LTE条件下,在以前的文件中开发的系列。在本系列的前一篇文章中描述了该代码。然而,在上一篇论文(系列论文的第四篇)中,数值结果是不切实际的。本文提出了一种近似,这是能够恢复的出射偏振剖面的可靠性。并证明了结果的收敛性。证明了当a > 1时,步长按1/N^a递减,从而使所得级数表现为绝对收敛的Riemann级数.然而,计算和观察到的线性偏振配置文件之间的协议仍然是定性的。这种差异被归因于平面平行大气模型,它不足以描述这些线形成的色球层。由于代码中所有积分都是数值的,因此它可能适用于更真实和更高维的模型大气。然而,对于像Na I D线那样具有超精细结构的线来说,这是耗时的。在Na I D 1中观察到的净线性偏振与安装在McMath-Pierce望远镜Kitt Peak上的偏振计ZIMPOL没有被本计算证实,可能是仪器偏振的假象。当Hanle效应在太阳第二光谱中起去极化作用时,相对于不考虑磁场的计算结果,仪器在Na I D2线中心观测到的较高的线偏振度可以证实仪器偏振的存在。所观察到的线性偏振过剩被发现在两个线中心,这也是本实验的仪器偏振补偿水平的0.1%的数量级相同。

英文摘要:

This paper presents a numerical application of a self-consistent theory of partial redistribution in non-LTE conditions, developed in previous papers of the series. The code was described in a previous paper of this series. However, in that previous paper (number IV of the series), the numerical results were unrealistic. The present paper presents an approximation, which was able to restore the reliability of the outgoing polarization profiles. The convergence of the results is also proved. It is demonstrated that the step increment decreases like 1/N^a, with a > 1, so that the results series behaves like a Riemann series, which is absolutely convergent. However, agreement between the computed and observed linear polarization profiles remains qualitative only. The discrepancy is assigned to the plane parallel atmosphere model, which is insufficient to describe the chromosphere, where these lines are formed. As all the integrals are numerical in the code, it could probably be adapted to more realistic and higher dimensioned model atmospheres. However, it is time consuming for lines having an hyperfine structure as the Na I D lines are. The net linear polarization observed in Na I D1 with the polarimeter ZIMPOL mounted on the McMath-Pierce telescope at Kitt Peak is not confirmed by the present calculations and could be an artefact of instrumental polarization. The presence of instrumental polarization could be confirmed by the higher linear polarization degree observed by this instrument in Na I D2 line center, with respect to the present calculation result, where the magnetic field is not accounted for, when the Hanle effect acts as a depolarizing effect in the Second Solar Spectrum. The observed linear polarization excess is found of the same order of magnitude 0.1% in both line centers, which is also comparable to the instrumental polarization compensation level of this experiment.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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