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

贫金属恒星的光谱学——非常古老的恒星缺乏比氦重的元素——是研究银河系中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，这将使阿帕奇点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凸起的金属贫乏恒星的元素丰度。这将使天文学家更好地了解核合成的位置和过程，以及银河系的化学富集历史。在这个项目中产生的数据也将对下一代大型红外望远镜进行的观测有用。该项目将为本科生提供参与先进光谱研究的机会，并为当地小学教师和高中学生提供社区参与的机会。利用先进的实验技术，威斯康星原子跃迁概率项目（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。这将允许确定精确的绝对原子跃迁概率。WATP的工作人员正在与一些研究贫金属恒星的领先专家合作，该项目代表了在近红外波长范围内测量过渡数据的集中努力的开始，特别是针对h波段的几个测量，以帮助大型远地点调查。该项目产生的数据将提高APOGEE的能力：a)确定重要参数log（g)，即恒星表面重力；b)区分主要的r（快速）过程和主要的s（低）过程n（中子）捕获核合成位点；c）确定更可靠的几种铁基团的丰度。除了这些近红外研究外，该项目还将对重要的n捕获镧系元素进行光学和紫外测量。本项目所开发和应用的定量原子光谱学方法也有望惠及分析化学等其他领域。该奖项反映了美国国家科学基金会的法定使命，并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.