Searching for Periodic Light Variability in Proto-Planetary Nebulae Candidates
Dr. Bruce Hrivnak
Arts and Sciences
Physics and Astronomy
The purpose of this research is to find periodic light variability in Proto-Planetary Nebulae (PPNe) candidates. These are Sun like stars that have expanded into a Red Giant and then ejected their outer layers. Pulsations in the star cause the light variability we observe, and the period of these pulsations can give us key information about the star itself, such as mass, radius and density. Using measurements of brightness over many years, the light curves can be analyzed to search for periodicity. Six PPNe candidates were studied in the southern-hemisphere for analysis. They were observed over an interval of five to six years and light curves were obtained from the data. These light curves were then analyzed by using a fitting program that preformed Fourier calculations to fit the curve to sinusoidal functions. Out of the six candidates, five were found to vary and three of which had periodic light variation. Periods ranged from 30 to 90 days. This is consistent with the periods of about 20 other studied and published PPNe in our galaxy. This research was supported by grants from the National Science Foundation and the Indiana Space Grant Consortium.
Willenbrink, Kathryn, "Searching for Periodic Light Variability in Proto-Planetary Nebulae Candidates" (2016). Symposium on Undergraduate Research and Creative Expression (SOURCE). 585.