The Study of Light Variability in a Sample of Proto-Planetary Nebulae

Faculty Sponsor

Dr. Bruce Hrivnak


Arts and Sciences



ORCID Identifier(s)


Document Type

Poster Presentation

Symposium Date

Summer 7-29-2015


We are studying the light variability of a subclass of evolved stars called proto-planetary nebulae. The proto-planetary nebulae phase is a stage near the end of the life cycle of stars like our sun as they evolve over time. Our goal is to determine the period of pulsation of each star, which can eventually be used to determine the size, mass, and density of the star. Using the 0.4 meter telescope and CCD detector located at the VU observatory, our group took many images of these objects over the course of the summer on every clear night. These images add another season of data to this project which began at VU in 2008. The computer software Period04 assists in finding periods within the full data set spanning from 2008 to 2014. With this program we have found periodicity in 5 of the ten stars assigned to us to analyze. Using these results we have been able to make some comparisons between some of the periods found in a star; for example, in IRAS20056, the first two periods in the R filter have a ratio of 2:1. There are also some stars whose periodicities show potential for a binary companion, these stars being IRAS20056 and IRAS20094. We will present some of the light curves and the initial period findings. This research was funded by the National Science Foundation through the MSEED Program, and grants to Professor Hrivnak from the National Science Foundation and from NASA through the Indiana Space Grant Consortium.

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