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

在这项合作工作中，布鲁斯·巴利克博士(华盛顿大学)、理查德·亨利博士(俄克拉荷马大学)和凯伦·凯特博士(威廉姆斯学院)将通过观测银河系早期几代恒星(“银河系”)和我们最近的兄弟邻星系M31喷出的富金属气体来补充现有的对演化最少和范围最广的恒星群的研究。这一结果将约束和挑战现有的所有星系如何演化或合并为其他星系的模型。此外，在垂死的恒星中形成氮和氧等元素的方法将通过测量它们的历史产生速度来确定。数据产品将包括所有银河系环境中行星状星云(PNE)的光谱和丰度数据库，使目前为地球附近PNE提取的样本的大小增加一倍。星系形成的历史必须从其最古老和演化最少的“化石”恒星的形状、动力学和化学来解读。这些恒星遍布所有大小星系延展的、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早期星系组装的模型，矮小星系持续同化的作用，年轻恒星被抛入古老的厚盘和晕中，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，以及在早期和高度混乱的宇宙中结构形成的速度和规模。作为这项研究的一部分，将为微弱星云开发分析数据和测量化学丰度的新方法。这些将在整个河外天文学中得到应用，如超新星早期的元素产生率和遥远类星体的化学性质。此外，作为这一研究计划的一部分，所有活动都是为了为本科生，特别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开发创造性的解释性想法，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.