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Laboratory Astrophysics for Studies of the Chemical Evolution of the Galaxy

研究银河系化学演化的实验室天体物理学

基本信息

批准号：
1814512
负责人：
Elizabeth Den Hartog
金额：
$ 33.65万
依托单位：
University of Wisconsin-Madison
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2022-11-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1814512&HistoricalAwards=false
关键词：
Laboratory Astrophysics Studies Chemical Evolution

项目摘要

The early Universe was almost completely made up of hydrogen and helium. Heavier chemical elements are produced in stars through a series of processes known as "nucleosynthesis". The earliest stars were likely quite different from stars today. Old stars, called "metal-poor" stars because they are deficient in heavier elements, were formed from the remnants of the earliest stars. Elemental abundances in metal-poor stars serve as a "fossil record" of our Galaxy and can help us understand the beginnings of nucleosynthesis. Testing theories of the early Universe requires very accurate measurements of elemental abundances in metal-poor stars. Accurate and precise abundance determination for a given element requires, first and foremost, accurate laboratory measurements of the spectral properties of that element. The goal of this research program is to conduct accurate, high-quality measurements of atomic data for the elements and to use these data to determine highly accurate abundances in metal-poor stars. This work could also lead to improvements that benefit other fields of applied science such as lighting and analytical chemistry. Training and mentoring of graduate and undergraduate students has been, and will continue to be, an important part of this program. The Wisconsin Atomic Transition Probability (WATP) program develops and applies advanced experimental techniques to measure accurate, absolute atomic transition probabilities. The transition probabilities are determined by combining branching fractions with radiative lifetimes measured using time-resolved laser-induced fluorescence. In recent years, a 3-meter echelle spectrometer was developed at the University of Wisconsin to measure very weak lines of Fe-group elements at ultraviolet wavelengths but is now optimized to work at optical wavelengths for applications to problems of ground-based astronomy. These weak lines are needed for abundance determination in stellar photospheres, because stronger lines of the abundant Fe-group elements are partially to deeply saturated and are therefore less ideal as abundance indicators. This project will complete work on Fe-group elements, with measurement of transition probabilities of weak lines of Sc II and Fe II. Subsequently, the WATP program will begin work on measuring transition probabilities of the alpha-elements, starting with Ca I. The newly measured transition probabilities will be used to determine accurate and precise abundances in the Sun and in metal-poor stars, and the relative abundances will be compared to models of nucleosynthesis.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.

早期的宇宙几乎完全由氢和氦组成。较重的化学元素在恒星中通过一系列被称为“核合成”的过程产生。最早的恒星可能与今天的恒星大不相同。古老的恒星，被称为“贫金属”恒星，因为它们缺乏更重的元素，是由最早的恒星的残余物形成的。贫金属恒星中的元素丰度可以作为我们银河系的“化石记录”，并可以帮助我们了解核合成的起源。测试早期宇宙的理论需要非常精确地测量贫金属恒星中的元素丰度。准确和精确地确定某一元素的丰度首先需要对该元素的光谱特性进行准确的实验室测量。该研究计划的目标是对元素的原子数据进行准确，高质量的测量，并使用这些数据来确定贫金属恒星的高精度丰度。这项工作也可能带来有益于其他应用科学领域的改进，如照明和分析化学。研究生和本科生的培训和指导一直是并将继续是该计划的重要组成部分。威斯康星州原子跃迁概率（WATP）计划开发和应用先进的实验技术来测量精确的，绝对的原子跃迁概率。的过渡概率确定通过结合分支分数与辐射寿命测量使用时间分辨的激光诱导荧光。近年来，威斯康星州大学研制了一台3米阶梯光栅光谱仪，用于测量紫外波长下铁族元素的非常微弱的谱线，但现在经过优化，可以在光学波长下工作，用于解决地基天文学的问题。这些弱谱线是恒星光球中丰度测定所必需的，因为丰富的铁族元素的强谱线是部分饱和到深度饱和的，因此作为丰度指标不太理想。该项目将完成铁族元素的工作，测量Sc II和Fe II弱线的跃迁概率。随后，WATP计划将开始测量α元素的跃迁概率，从Ca I开始。新测量的跃迁概率将用于确定太阳和贫金属恒星的准确和精确的丰度，相对丰度将与核合成模型进行比较。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

项目成果

期刊论文数量（14）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Iron-peak Element Abundances in Warm Very Metal-poor Stars

DOI：
10.3847/1538-4357/accd62
发表时间：
2023-04
期刊：
The Astrophysical Journal
影响因子：
0
作者：
C. Sneden;A. Boesgaard;J. Cowan;I. Roederer;E. A. Den Hartog;J. Lawler
通讯作者：
C. Sneden;A. Boesgaard;J. Cowan;I. Roederer;E. A. Den Hartog;J. Lawler

Detailed Iron-peak Element Abundances in Three Very Metal-poor Stars

DOI：
10.3847/1538-4357/ab6aa9
发表时间：
2020-01
期刊：
The Astrophysical Journal
影响因子：
0
作者：
J. Cowan;C. Sneden;I. Roederer;J. Lawler;E. A. Hartog;J. Sobeck;A. Boesgaard
通讯作者：
J. Cowan;C. Sneden;I. Roederer;J. Lawler;E. A. Hartog;J. Sobeck;A. Boesgaard

Energy Levels of Singly Ionized and Neutral Hafnium

单电离铪和中性铪的能级