Collaborative Research: Galactic Archaeology from Careful Modeling of Old Stars

合作研究：从对老恒星的仔细建模中进行银河考古学

• 批准号: 2206264
• 负责人: Alexander Ji
• 金额: $ 42.45万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2206264&HistoricalAwards=false
• 关键词: Collaborative; Research; Galactic; Archaeology; Careful

The history of star formation of the entire universe is hidden in the elements making up the oldest stars in our Milky Way Galaxy. Astronomers start to unravel that history by careful observations of metal-poor (old) red giant stars. Making further progress requires numerically modeling the observations. These investigators will enhance our understanding by creating more exact models. Their work is important because in the coming years, large observational spectroscopic surveys of our Milky Way Galaxy will push the distance and age frontiers of our knowledge. The investigators plan to help analyze enormous datasets using fast, physically motivated analysis tools. They will derive the stars’ current physical parameters and chemical compositions. Currently, most models use an approximation in stellar spectral analysis, called Local Thermodynamic Equilibrium (LTE). The investigators will use more realistic, but computationally expensive, non-LTE models. The investigators will significantly improve the accuracy of derived elemental abundances found in the metal-poor red giant stars, giving us a better understanding of the history of star formation. Additionally, the project will develop opportunities for under-represented and minority K-12 students from Florida schools to undertake research using the local teaching observatory and telescopes. It will also improve diversity in astronomy through equitable and inclusive mentoring of under-represented minority undergraduate students in summer research projects at the University of Chicago.This collaborative project between the University of Florida and the University of Chicago will enable fast, homogeneous derivation of non-LTE stellar parameters and chemical abundances by implementing non-LTE in full spectrum synthesis and using machine learning techniques to efficiently emulate the non-LTE grids. The results will be applied on industrial scales to large surveys of red giant stars covering both optical and infrared wavelengths. The project will produce user-friendly, publicly available codes that allow other astronomers to apply non-LTE analyses to their spectra.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.

整个宇宙的恒星形成历史隐藏在构成银河系最古老恒星的元素中，天文学家开始通过对贫金属（古老）红巨星的仔细观察来解开这一历史，要取得进一步的进展需要在数值上取得进展。这些研究人员将通过创建更精确的模型来增强我们的理解，因为在未来几年，对我们银河系的大型观测光谱调查将推动我们知识的距离和年龄边界。帮助分析巨大他们将使用快速、物理驱动的分析工具得出恒星当前的物理参数和化学成分。目前，大多数模型使用恒星光谱分析中的近似值，称为局部热力学平衡（LTE）。研究人员将使用更现实的方法。计算成本高昂的非 LTE 模型将显着提高在贫金属红巨星中发现的元素丰度的准确性，使我们更好地了解恒星形成的历史。此外，该项目还将开发机会。为来自佛罗里达州学校的代表性不足和少数族裔的 K-12 学生使用当地教学天文台和望远镜进行研究 它还将通过对大学夏季研究项目中代表性不足的少数族裔本科生的公平和包容性指导来提高天文学的多样性。佛罗里达大学和芝加哥大学之间的这个合作项目将通过在全频谱合成中实现非 LTE 并使用机器学习技术有效地模拟，实现非 LTE 恒星参数和化学丰度的快速、均匀推导该项目的结果将应用于工业规模的红巨星观测，涵盖光学和红外波长，将产生用户友好的、公开的代码，允许其他天文学家应用非 LTE 分析。该奖项反映了 NSF 的法定使命，并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，被认为值得支持。

项目成果

Metal Mixing in the r-process Enhanced Ultrafaint Dwarf Galaxy Reticulum II*

r 过程中的金属混合增强型超微弱矮星系网状网 II*

• DOI: 10.3847/1538-3881/acad84
• 发表时间: 2023-02
• 期刊: The Astronomical Journal
• 作者: Ji, Alexander P.;Simon, Joshua D.;Roederer, Ian U.;Magg, Ekaterina;Frebel, Anna;Johnson, Christian I.;Klessen, Ralf S.;Magg, Mattis;Cescutti, Gabriele;Mateo, Mario;et al
• 通讯作者: et al