Damped Lyman-alpha (DLA) and sub-DLA absorbers in quasar spectra provide the most sensitive tools for measuring element abundances of distant galaxies. Estimation of abundances from absorption lines depends sensitively on the accuracy of the atomic data used. We have started a project to produce new atomic spectroscopic parameters for optical/UV spectral lines using state-of-the-art computer codes employing very broad configuration interaction basis. Here we report our results for Zn II, an ion used widely in studies of the interstellar medium (ISM) as well as DLA/sub-DLAs. We report new calculations of many energy levels of Zn II, and the line strengths of the resulting radiative transitions. Our calculations use the configuration interaction approach within a numerical Hartree-Fock framework. We use both non-relativistic and quasi-relativistic one-electron radial orbitals. We have incorporated the results of these atomic calculations into the plasma simulation code Cloudy, and applied them to a lab plasma and examples of a DLA and a sub-DLA. Our values of the Zn II λλ 2026, 2062 oscillator strengths are higher than previous values by 0.10 dex. Cloudy calculations for representative absorbers with the revised Zn atomic data imply ionization corrections lower than calculated before by 0.05 dex. The new results imply Zn metallicities should be lower by 0.1 dex for DLAs and by 0.13-0.15 dex for sub-DLAs than in past studies. Our results can be applied to other studies of Zn II in the Galactic and extragalactic ISM.
Chemical evolution of the Universe at 0.7 < z < 1.6 derived from abundance diagnostics of the broad-line region of quasars
我们提出了一个分析Mg II $\lambda2798$和Fe II紫外线发射线的档案斯隆数字巡天（SDSS）类星体，探索诊断镁铁丰度比在宽线区域云。我们的样本由17,432个类星体组成，这些类星体是从SDSS数据发布7中选出的，红移范围为$0.72 < z < 1.63$。Mg II等效宽度（EW）和爱丁顿比之间存在较强的正相关关系，而Fe II EW和爱丁顿比之间仅存在较弱的正相关关系。为了调查镁II和铁II发射线的这些不同的行为的起源，我们已经进行了光电离计算，使用云代码，其中考虑了最近的混响映射研究的约束。计算结果表明，Mg Ⅱ和Fe Ⅱ的发射谱线出现在光电离云的不同区域，它们与爱丁顿比的EW相关可以通过改变云的气体密度来解释。这些结果表明，Mg II/Fe II通量比，这已被用作一阶代理的Mg/Fe丰度比的化学演化研究类星体发射线，在很大程度上取决于云气体密度。通过校正这种密度依赖性，我们提出了新的诊断的Mg/Fe丰度比的宽线区域云。比较得出的Mg/Fe丰度比与化学演化模型，我们认为，$α$富集的质量损失，从贫金属的中等质量的恒星发生在$z\sim2$或更早。
Tracing the Early Milky Way with Globular Clusters: The Diagnostic Power of Neutron-Capture Elements
Istituto Nazionale di Astrofisica – Osservatorio Astrofisico di Arcetri（国家天体物理研究所-阿切特里天文台）；Istituto Nazionale di Astrofisica – Osservatorio Astronomico di Padova（国家天体物理研究所-帕多瓦天文台）；Istituto Nazionale di Astrofisica - Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（国家天体物理研究所-博洛尼亚天文与空间科学观测站）
Observational constraints on the origin of the elements. X. Combining NLTE and machine learning for chemical diagnostics of 4 million stars in the 4MIDABLE-HR survey
Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；Heidelberg University（海德堡大学）；Research School of Astronomy & Astrophysics, The Australian National University（澳大利亚国立大学天文与天体物理研究学院）；Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik（海德堡大学天文学中心理论天体物理研究所）；Lund Observatory, Division of Astrophysics, Department of Physics, Lund University（隆德大学物理学系天体物理分部隆德天文台）；Faculty of Mathematics and Physics, University of Ljubljana（卢布尔雅那大学数学与物理学院）；Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange（蔚蓝海岸大学蔚蓝海岸天文台法国国家科学研究中心拉格朗日实验室）；Institute of Astronomy, University of Cambridge（剑桥大学天文学研究所）；Leibniz-Institut für Astrophysik Potsdam (AIP（波茨坦阿基米德天体物理研究所）
