Numerical Simulations of Non-Equilibrium Plasmas and Their Spectra

我们对宇宙化学演化的大部分理解来自于对星际气体中产生的发射或吸收谱线的分析。这个项目同时在几个广泛的前沿进行攻击，从附近的HII区域延伸到发光的类星体，共同的主题是开发绘制其化学演化所需的工具。这项工作主要集中在开发和应用大规模等离子体模拟代码Cloudy。这是一个多管齐下的努力，结合了观测天体物理学，数值模拟，原子和分子物理学。这些步骤紧密地交织在一起，从猎户座星云到巨大的河外H II区剑鱼座30，最终到遥远类星体光谱中的吸收线所看到的中间系统。从一个完整的中性氢分子模型开始，通过一个完全自一致的光谱模拟，该项目将扩展到类氦物种，并在原始氦丰度上进行重要的首次应用。通过其他扩展，结果应该是对气体如何从完全分子状态流动的完全自洽的描述，最终进入通过光电离形成离子的区域，从而对整个环境进行几乎无参数的描述。这些模型将在猎户座星云和剑鱼座30号的非常深的光学光谱中进行测试，剑鱼座30号是最近的巨大的河外HII区域。这个项目核心的光谱模拟代码被其他研究人员用于每年发表一百多篇论文的工作。因此，在学生的大力参与下，包括作为他们博士论文的一部分，代码开发对社区产生了非常广泛的影响。研究人员还将利用这个项目的结果来协助正在制定的一项计划，该计划将把肯塔基州中部的在职教师带到他的大学校园，进行研究简报和教学策略讨论。

AST-0307720FerlandMuch of our understanding of the chemical evolution of the cosmos comes from the analysis of emission or absorption lines produced in interstellar gas. This project is a simultaneous attack on several broad fronts extending from nearby HII regions to luminous quasars with the common theme of developing the tools needed to chart their chemical evolution. Much of this work centers on the development and application of the large-scale plasma simulation code Cloudy. This is a multi-pronged effort that combines observational astrophysics, numerical simulations, and atomic and molecular physics. These steps are strongly interwoven and progress from the Orion Nebula, to the giant extragalactic H II region 30 Doradus, and eventually to the intervening systems seen by their absorption lines in spectra of distant quasars. Starting with a complete model of the neutral hydrogen molecule, with a fully self-consistent spectral simulation, the project will then extend to helium-like species, with an important first application to the primordial helium abundance. With other extensions, the result should be a fully self-consistent description of how gas flows from its fully molecular state, eventually into regions where ions are formed by photo-ionization, resulting in an almost parameter-free description of the entire environment. The models will be tested against very deep optical spectroscopy of the Orion Nebula and of 30 Doradus, the nearest giant extragalactic HII region.The spectral simulation code at the heart of this project is used by other researchers in work that produces over a hundred papers a year. Code development, with strong involvement by students, including as parts of their doctoral theses, therefore has a very wide impact on the community. Results from this project will also be used by the researcher to assist with a scheme under development which will bring in-service teachers from central Kentucky to his University campus for research briefings and teaching strategy discussions.