Accurate Atomic Transition Probabilities in Aid of APOGEE and the Study of Galactic Chemical Evolution

贫金属恒星（缺乏比氦重的元素的非常古老的恒星）的光谱学是研究银河系化学元素起源的最重要手段之一。该研究项目将主要产生高质量的红外（IR）原子光谱和跃迁概率的实验室测量结果，这将使Apache Point天文台银河演化实验（APOGEE）光谱调查能够准确地确定居住在银河系尘埃隆起中的贫金属恒星的元素丰度。 这将使天文学家能够更好地了解核合成的地点和过程以及银河系的化学富集历史。 该项目产生的数据也将有助于利用下一代大型红外望远镜进行观测。该项目将为本科生提供参与高级光谱研究的机会，以及与当地小学教师和高中学生进行社区参与的机会。利用先进的实验技术，威斯康星州原子跃迁概率计划（WATP）的研究小组将测量镧系元素和铁族元素的高分辨率近红外光谱，以及关键镧系元素的光学和紫外（UV）光谱。 这将允许确定准确的，绝对的原子跃迁概率。该项目的工作人员正在与一些主要专家合作研究贫金属星，这一项目标志着开始集中努力测量近红外波长范围内的跃迁数据，特别是在H波段进行几次测量，以协助大规模的APOGEE调查。该项目产生的数据将提高APOGEE的能力，以a）确定重要参数log（g），或恒星表面重力，B）区分主要是r（快速）过程和主要是s（低）过程n（中子）捕获核合成位点，和c）确定更可靠的几个Fe族物种的丰度。除了这些近红外研究，该项目将产生重要的n-捕获镧系元素的光学和紫外测量。 该项目中开发和应用的定量原子光谱方法也有望使分析化学等其他领域受益。该奖项反映了NSF的法定使命，通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Spectroscopy of metal-poor stars – very old stars deficient in elements heavier than helium – is one of the most important means to study the origin of chemical elements in the Milky Way. This research project will primarily generate high quality laboratory measurements of infrared (IR) atomic spectra and transition probabilities that will enable the Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectroscopic survey to accurately determine elemental abundances in metal-poor stars residing in the dusty bulge of the Milky Way. This will allow astronomers to better understand the sites and processes of nucleosynthesis and the chemical enrichment history of the Galaxy. Data generated in this project will also be useful for observations undertaken with the next generation of large IR telescopes. This project will provide opportunities for undergraduate students to be involved in advanced spectroscopic research, as well as opportunities for community engagement with local elementary school teachers and high school students.Using advanced experimental techniques, the research team of the Wisconsin Atomic Transition Probability program (WATP) will measure high resolution near IR spectra of lanthanide and Fe-group elements, and optical and ultraviolet (UV) spectra of key lanthanide elements. This will permit determination of accurate, absolute atomic transition probabilities. WATP personnel are collaborating with some of the leading experts in the study of metal-poor stars, and this project represents the beginning of a focused effort to measure transition data in the near IR wavelength range, specifically targeting several measurements in the H-band, in aid of the large APOGEE survey. The data generated by this project will improve the ability of APOGEE to a) determine the important parameter log(g), or stellar surface gravity, b) discriminate between predominantly r(apid)-process and predominantly s(low)-process n(eutron)-capture nucleosynthesis sites, and c) determine more reliable abundances of several Fe-group species. In addition to these near IR studies, this project will generate optical and UV measurements of important n-capture lanthanide elements. The methods of quantitative atomic spectroscopy developed and applied in this project are also expected to benefit other fields such as analytical chemistry.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.