Interface of Equation-of-State, Atomic Data and Opacities in the Solar Problem

Q1 Earth and Planetary Sciences

Monthly Notices of the Royal Astronomical Society: Letters Pub Date : 2023-10-04 DOI:10.1093/mnrasl/slad154

Anil K Pradhan

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Abstract

ABSTRACT The dependence of the Rosseland Mean Opacity (RMO) on the equation of state and the number of included atomic levels of iron ions prevalent at the solar radiative/convection boundary is investigated. The ‘chemical picture’ Mihalas–Hummer–Däppen (MHD) equation-of-state (EOS), and its variant QMHD–EOS, are studied at two representative temperature–density sets at the base of the convection zone and the Sandia Z experiment: (2 × 106 K, 1023/cc) and (2.11 × 106 K, 3.16 × 1022/cc), respectively. It is found that whereas the new atomic data sets from accurate R-matrix calculations for opacities (RMOP) are vastly overcomplete, involving hundreds to over a thousand levels of each of the three Fe ions considered – Fe xvii, Fe xviii, Fe xix – the EOS constrains contributions to RMOs by relatively fewer levels. The RMOP iron opacity spectrum is quite different from the Opacity Project distorted wave model and shows considerably more plasma broadening effects. This work points to possible improvements needed in the EOS for opacities in high-energy–density plasma sources.

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太阳问题中状态方程、原子数据和不透明性的接口

摘要研究了在太阳辐射/对流边界上流行的铁离子的Rosseland平均不透明度(RMO)与状态方程和包含原子能级数的关系。在对流区底部两个具有代表性的温度-密度集和Sandia Z实验(2 × 106 K, 1023/cc)和(2.11 × 106 K, 3.16 × 1022/cc)下，研究了“化学图”Mihalas-Hummer-Däppen (MHD)状态方程(EOS)及其变体QMHD-EOS。研究发现，从精确的r矩阵计算中得到的新原子数据集(RMOP)非常不完整，涉及到三种铁离子(fexvii, fexviii, fexix)中的每一种的数百到1000多个水平，而EOS对RMOs的限制相对较少。RMOP铁不透明谱与不透明项目畸变波模型有很大不同，显示出更多的等离子体展宽效应。这项工作指出了EOS在高能量密度等离子体源的不透明度方面可能需要改进的地方。

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来源期刊

Monthly Notices of the Royal Astronomical Society: Letters Earth and Planetary Sciences-Space and Planetary Science

CiteScore

8.80

自引率

0.00%

发文量

136

期刊介绍： For papers that merit urgent publication, MNRAS Letters, the online section of Monthly Notices of the Royal Astronomical Society, publishes short, topical and significant research in all fields of astronomy. Letters should be self-contained and describe the results of an original study whose rapid publication might be expected to have a significant influence on the subsequent development of research in the associated subject area. The 5-page limit must be respected. Authors are required to state their reasons for seeking publication in the form of a Letter when submitting their manuscript.