Collaborative Research: PNe as Probes of the Early Chemical History of the Galaxy and M31

在这次合作中，Bruce Balick博士（华盛顿大学）、Richard Henry博士（俄克拉荷马大学）和Karen Kwitter博士（威廉姆斯学院）将通过观察银河系（“银河系”）和我们最近的兄弟星系M31中早期恒星喷射出的富含金属的气体，来补充现有的最不进化和最扩展的恒星群的研究。这些结果将限制和挑战现有的所有星系如何演化或合并到其他星系的模型。此外，在垂死的恒星中，氮和氧等元素形成的方式将通过测量它们产生的历史速率来确定。数据产品将包括所有星系环境中行星状星云（PNe）的光谱和丰度数据库，是目前地球附近行星状星云样本的两倍。星系形成的历史必须从其最古老和最不进化的“化石”恒星的形状、动力学和化学特征中解读出来。这些恒星遍布所有大小星系的延伸的、基本上未受干扰的外部区域。这些恒星的化学和运动学有助于限制星系早期聚集的模型，矮星系持续同化的作用，年轻恒星向旧厚盘和晕的抛射，来自原子核的重元素反馈，超新星和AGB质量损失，暗物质的影响，以及早期和高度混沌宇宙中结构形成的速率和大小尺度。作为这项研究的一部分，将开发用于分析微弱星云的数据和测量化学丰度的新方法。这些将在整个星系外天文学领域得到应用，如早期超新星的元素产生率和遥远类星体的化学性质。此外，作为这个研究项目的一部分，所有的活动都是为了给本科生，尤其是那些来自代表性不足群体的学生提供研究机会而设计的。学生将直接参与分析数据和发展创造性的解释思想，形成实践科学和研究的核心动机，并理解其在现代社会中的作用。

In this collaborative effort, Drs Bruce Balick (University of Washington), Richard Henry (University of Oklahoma), and Karen Kwitter (Williams College) will complement extant studies of the least evolved and most extended stellar populations with observations of the metal-enriched gas ejected from early generations of stars in the Milky Way (the "Galaxy") and our nearest sibling neighbor galaxy, M31. The results will constrain and challenge extant models of how all galaxies evolved or merged into others. In addition, the means by which elements such as nitrogen and oxygen have been formed in dying stars will be determined by measuring the historical rates of their production. The data products will include databases of spectra and abundances of planetary nebulae (PNe) in all galactic environments, doubling the size of the present sample derived for of PNe near the Earth. The history of galaxy formation must be read from the shape, dynamics, and chemistry of its oldest and least evolved "fossil" stars. These stars are found throughout the extended, largely undisturbed outer regions of all galaxies, large and small. The chemistry and kinematics of these stars help to constrain the models for the early assembly of galaxies, the role of ongoing assimilation of dwarf galaxies, the ejections of younger stars into the old thick disk and halo, the feedback of heavy elements from the nucleus, supernovae, and AGB mass loss, the influence of dark matter, and the rates and size scales of the formation of structure in the early and highly chaotic universe. As a part of this research, new methods for analyzing the data and measuring chemical abundances will be developed for faint nebulae. These will have application throughout extragalactic astronomy in such areas as element production rates in very early supernovae and the chemical properties of distant quasars. In addition, all of the activities that will take place as a part of this research program have been conceived with the goal of providing research opportunities for undergraduate students, especially those students from underrepresented groups. The students will be direct participants in analyzing the data and developing creative interpretive ideas that form the core motivation for practicing science and research, and for understanding its role in modern society.