Damped Lyman Alpha Systems as Probes of Nitrogen Synthesis in the Early Universe

阻尼莱曼阿尔法系统作为早期宇宙中氮合成的探测器

• 批准号: 0307118
• 负责人: Richard Henry
• 金额: --
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0307118&HistoricalAwards=false
• 关键词: Damped; Lyman; Alpha; Systems; Probes

AST-0307118HenryThis project will study the origin of Nitrogen using damped Lyman-alpha systems (DLAs) as probes of chemical evolution in the early Universe. The basic uncertainty is whether the principal contribution comes from slower-evolving stars which eject material via planetary nebulae and end as white dwarfs, or more massive stars which evolve rapidly and spread elements heavier than hydrogen and helium by ending with a supernova explosion. The difference in speed of these two processes is the key to the investigation: the time it takes a lower-mass star to distribute elements is a significant fraction of the age of DLAs, which are absorption-line systems of low metallicity and high redshift. The researcher will numerically calculate detailed chemical evolution models and compare them to observations provided by colleagues. Some especially well-observed DLAs will be used to constrain star formation histories. This study will also test ideas relating the distribution of DLA properties either to characteristics of the initial stellar mass function, or to the effects of Population III nucleosynthesis.A significant contribution to astronomy will continue to be the critical evaluation of published stellar yields based on their predictive success, an activity for which this investigator is particularly noted. This work will affect our understanding of an abundant and biologically important element. The research will result in one doctoral dissertation and will enhance collaborations both in the US and abroad.***

AST-0307118Henry该项目将使用阻尼莱曼-α系统（DLA）作为早期宇宙化学演化的探针来研究氮的起源。 基本的不确定性在于，主要贡献是否来自于较慢演化的恒星（通过行星状星云喷射物质并最终形成白矮星），还是来自较大质量的恒星（快速演化并以超新星爆炸结束，传播比氢和氦更重的元素）。 这两个过程的速度差异是研究的关键：低质量恒星分配元素所需的时间占 DLA 年龄的很大一部分，DLA 是低金属丰度和高红移的吸收线系统。 研究人员将对详细的化学演化模型进行数值计算，并将其与同事提供的观察结果进行比较。 一些观测得特别好的 DLA 将被用来限制恒星形成的历史。 这项研究还将测试将 DLA 特性的分布与初始恒星质量函数的特征或族 III 核合成的影响相关的想法。对天文学的重大贡献将继续是基于其预测成功对已发表的恒星产量进行严格评估，这是本研究人员特别关注的一项活动。 这项工作将影响我们对丰富且具有生物学重要性的元素的理解。 该研究将产生一篇博士论文，并将加强美国和国外的合作。***