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

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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.