RUI: Variability - A Key Probe of the Properties and Evolution of Post-AGB Stars and Proto-Planetary Nebulae

该项目将确定原行星状星云（PPNe）的基本物理性质。在太阳和中等质量恒星的演化过程中，这些天体从演化的红巨星过渡到行星状星云阶段。这项新的研究将扩大现有的样本，包括富氧恒星。它将包括附近大小麦哲伦星云星系中的一些PPNe。将变异性结果与颜色和径向速度数据相结合，将允许直接确定恒星半径和光度。预计在该项目结束时获得的长时间序列数据集（在某些情况下长达20年）将首次揭示脉动期的实时演化，这是对演化模型的额外观测约束。双星及其对星云形状的影响将通过精确的径向速度观测来研究。该研究项目涉及国内和国际合作。预计这项活动还将对科学学生的培训、文科学生的教育以及瓦尔帕莱索大学的科学基础设施产生积极影响。本研究项目的方法和结果也将纳入通识教育天文学课程，部分观测数据将用于实验室研究经验。赫里夫纳克博士和学生研究助理将在瓦尔帕莱索天文台开展一个公开参观项目和社区外展活动，并定期向社区和专业人士介绍天文学。

This project will determine the basic physical properties of proto-planetary nebulae (PPNe).These are objects in transition from the evolved red giants to the planetary nebula phase in the evolution of solar- and intermediate-mass stars. This new study will enlarge current samples to include oxygen-rich stars. It will include some PPNe in the nearby Large and Small Magellanic Cloud galaxies. Combining the variability results with color and radial velocity data will permit a direct determination of the stellar radius and luminosity. It is also anticipated that the long time-series data set (up to 20 years in some cases) obtained by the end of this project will reveal, for the first time, real-time evolution in pulsation periods, an additional observational constraint on the evolutionary models. Binarity and its effect on the shaping of the nebulae will be investigated through precise radial velocity observations.The research project involves both national and international collaborations. The activity is also expected to have a positive impact on the training of science students, the education of liberal arts students, and on the infrastructure for science at Valparaiso University. The methods and results from this research project will also be integrated into the general education astronomy classes and some of the observational data will be used in laboratory research experiences. Dr. Hrivnak and student research assistants will carry out a program of public open house viewing at the Valparaiso Observatory and community outreach, and make regular community and professional presentations on astronomy.