RII Track 4: Heavy Element Isotopic Characterization of Stardust

该项目将在实验室中研究微观星尘颗粒，以寻找宇宙元素起源这一最基本问题的答案，并了解构成我们太阳系的物质的特性。这项研究的结果有望带来一种潜在的革命性的理解，即重元素是如何在超新星和一些不太为人所知的外来恒星中产生的，这些恒星为我们的太阳系提供了初始物质。该奖学金项目将允许PI与劳伦斯利弗莫尔国家实验室开展长期合作，这将使她能够建立一个高产且声誉良好的宇宙化学实验室，该实验室在高度跨学科的领域表现出色，并为路易斯安那大学拉斐特分校新的地球与能源科学多学科博士课程做出贡献。一个成功的项目将使她在她的大学获得最先进的分析设备；因此，增加了PI与路易斯安那州和世界各地跨学科科学家的合作。这笔拨款还将用于指导和培训一名代表性不足的博士生，使其掌握可用于纯研究和/或众多工业应用的前沿分析技术；因此，为增加STEM领域的多样性做出了重要贡献。星尘颗粒是真正的微观到亚微观的恒星碎片，它们在垂死恒星的冷却喷射物中凝结，早于我们太阳系的形成。该项目的主要目标是通过研究星尘颗粒中的这些特征，通过核合成来探测恒星中产生重核的s-， r-， p-和i-过程。这种理解不仅将为这些恒星的核合成模型提供更严格的约束，而且还将为旨在构建这些星尘颗粒凝聚的化学和物理环境的清晰图像的热力学和动力学演化模型提供更严格的约束。在这笔奖学金的帮助下，PI将获得劳伦斯利弗莫尔国家实验室（LLNL）最新的，最先进的，中性激光电离（LION）共振电离质谱（RIMS）设备的扩展访问权，并与负责科学家合作。LION允许PI和她的研究生系统地测量来自超新星的单个微米尺寸的石墨星尘颗粒和具有i过程特征的颗粒中的重微量元素的同位素组成。RIMS是一种测量重同位素的强大技术，因为它可以选择性地电离感兴趣的元素并消除等压干扰。在这一年里，PI和她的研究生将花时间在国内机构准备太阳能前石墨样品，然后前往LLNL获取谷物的测量数据。为了根据它们的恒星来源来描述这些颗粒的特征，通过与理论天体物理学家的合作，将获得的数据与天体物理核合成模型进行比较。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。

This project will study microscopic stardust grains in the laboratory to find answers to the most fundamental question of the origin of elements in the Universe and to understand the properties of the materials that formed our solar system. The results from this study promise to bring about a potentially transformative understanding of how heavy elements are created in supernovae and some lesser-known exotic stars that contributed starter materials to our solar system. The fellowship project will allow the PI to develop a long-term collaboration with Lawrence Livermore National Laboratory that will enable her to establish a productive and reputable cosmochemistry laboratory that excels in a highly interdisciplinary field and contribute to the new Earth and Energy Sciences multidisciplinary PhD program at the University of Louisiana Lafayette. A successful project will enable her to obtain state-of-the-art analytical equipment at her university; thus, increasing the PI’s collaborations with interdisciplinary scientists across the state of Louisiana and the world. This grant will also be used to mentor and train an underrepresented PhD student in cutting edge analytical techniques that can be used in pure research and/or numerous industrial applications; thus, contributing to the imperative effort of increasing diversity in STEM fields.Stardust grains are bona fide microscopic to sub-microscopic pieces of stars that condensed in the cooling ejecta of dying stars and pre-date the formation of our solar system. The main goal of this project is to probe s-, r-, p-, and i-processes that make heavy nuclei in stars, via nucleosynthesis, by studying these signatures in stardust grains. This understanding will not only provide tighter constraints on the nucleosynthesis models of these stars but also to the thermodynamic and kinetic evolution models that aim to construct a clear picture of the chemical and physical circumstellar environments in which these stardust grains condensed. With the aid of this fellowship, the PI will gain extended access to the new, state-of-the-art, Laser Ionization of Neutrals (LION) resonant ionization mass spectrometry (RIMS) facility at Lawrence Livermore National Laboratory (LLNL) and collaborate with the scientist-in-charge. LION allows the PI and her graduate student to systematically measure isotopic compositions of heavy trace elements in individual micron-sized graphitic stardust grains from supernovae and grains with i-process signatures. RIMS is a powerful technique to measure heavy isotopes as it selectively ionizes elements of interest and eliminates isobaric interferences. The PI and her graduate student will spend time during the year preparing the presolar graphitic samples at the home institution and then travel to LLNL to acquire measurements on grains. In order to characterize the grains according to their stellar sources, the data obtained will be compared to astrophysical nucleosynthesis models through collaborations with theoretical astrophysicists.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.