Enrichments of Trans-Iron Elements in Planetary Nebulae: Probing Stellar Evolution and Nucleosynthesis

我们身体中的原子，除了氢之外，都是由太阳系诞生之前恒星内部的核反应产生的。 研究人员将研究像我们的太阳这样的恒星产生这些化学元素的过程。 当我们的太阳达到大约100亿年的年龄时，它将膨胀成为一颗红巨星星星。 这样的红巨星后来抛出物质，形成膨胀的发光云，称为行星状星云。 天文学家观察来自这些星云的光来研究它们的化学性质。 新的恒星制造的元素流入太空并遍布我们的银河系。该项目位于多个科学学科的交叉点，并激励不同教育水平的学生进入STEM领域，这满足了国家的重要需求。 问题是“元素从何而来？“具有广泛的吸引力。 该项目将支持得克萨斯大学的一名研究生以及得克萨斯大学和西格鲁吉亚大学的本科生，这两所大学都有大量代表性不足的少数民族（分别是西班牙裔和非洲裔美国人）。 通过教师讲习班，调查人员将接触到大量的高中生。 纯天文学研究与物理学的其他领域有着密切的联系。 例如，一些研究人员新检测到的发射谱线（例如，铷，镉和碲）的能量与预测的不同，提高了我们对地球上发现的原子的理解。研究人员的主要研究方法是高光谱分辨率（R 40，000）的近红外和光学光谱，以优化弱发射线的检测并避免与其他元素的混合。 他们使用星云丰度分析的标准程序，从线通量测量中得出离子和元素丰度，但采用了新的原子模型。 目标是区分哪些演化模型是最现实的，并以经验的方式建立1-8个太阳质量的恒星对银河系化学演化的贡献。 这类恒星的化学产额是银河系考古学和推断银河系恒星形成历史的关键因素。

The atoms in our bodies, apart from hydrogen, were produced by nuclear reactions deep within stars that lived and died before our Solar System was born. The investigators will study the production of these chemical elements by stars like our Sun. When our Sun reaches an age of about 10 billion years, it will expand to become a red giant star. Such red giant stars later throw off material and form expanding, glowing clouds called planetary nebulae. Astronomers observe the light coming from these nebulae to study their chemical properties. The new, star-made elements flow into space and spread throughout our Milky Way Galaxy.This project lies at the crossroads of several scientific disciplines and motivates students over a range of educational levels to enter STEM fields, which addresses an important national need. The question "Where did the elements come from?" has broad appeal. The project will support a graduate student at the University of Texas (UT) and undergraduates at both UT and the University of West Georgia, which have substantial populations of underrepresented minorities (Hispanic and African-American respectively). Through teacher workshops the investigators will reach large numbers of high school students. Pure astronomical research has strong connections to other areas of physics. For example, some of the investigators' newly detected emission lines (e.g., rubidium, cadmium, and tellurium) were found at different energies than predicted, improving our understanding of atoms found on the Earth. The investigators' primary research method is near infrared and optical spectroscopy at high spectral resolution (R 40,000) to optimize detection of weak emission lines and avoid blends with other elements. They use standard procedures of nebular abundance analysis to derive ionic and elemental abundances from line flux measurements but incorporate new atomic models. The goals are to distinguish which evolutionary models are most realistic and to empirically establish the contributions of 1-8 solar mass stars to Galactic chemical evolution. The chemical yield of this numerous class of stars is a key ingredient for galactic archeology and inferring the star-forming history of the Milky Way Galaxy.