The Transition from Evolved Star to Planetary Nebula: An Observational Study

哈丽特·迪纳斯坦博士将使用几种观测技术来解决恒星如何从后期红巨星转变为行星状星云并最终转变为白矮星的问题。这一短暂的进化事件是恒星生命历史上的一个关键转折点，但人们对它的理解仍然不够透彻。迪纳斯坦博士将研究并定义行星状星云电离核心周围的大量残余中性包层的特性。最近的工作已经证明了这些包层的存在，并说明了使用光学和红外光谱来确定它们的参数。关于中性物质的数量和分布的数据对于质量损失和行星状星云形成过程的任何综合图像都是必不可少的。迪纳斯坦博士还将研究进化的双极星云，它代表了一个可识别的行星状星云出现之前的阶段。通过结合几个波长的观测结果，迪纳斯坦博士将能够确定这些结构的一般几何形状，并确定主要的质量和发射成分。对处于不同发展阶段的天体进行比较，应该能够阐明恒星演化这一短暂和转变阶段的演化过程。

Dr. Harriet Dinerstein will use several observational techniques to address the question of how stars undergo the transformation from late stage red giants into planetary nebulae and ultimately white dwarfs. This transitory evolutionary episode is a crucial turning point in stellar life histories, yet it is still not well understood. Dr. Dinerstein will investigate and define the properties of the massive residual neutral envelopes around the ionized cores of planetary nebulae. Recent work has demonstrated the presence of these envelopes and illustrated the use of optical and infrared spectroscopy to determine their parameters. Data on the amount and distribution of neutral material are essential to any comprehensive picture of the mass loss and planetary nebula formation process. Dr. Dinerstein will also study evolved bipolar nebulae, which represent the phase immediately preceding the appearance of a recognizable planetary nebula. By combining results of observations at several wavelengths, Dr. Dinerstein will be able to determine the general geometry of these structures and locate the main mass and emission components. The comparison of objects at different stages of development should clarify the evolutionary progression through this transient and transforming stage of stellar evolution.