Searching for Periodicity in a Sample of Evolved Stars


Sean EganFollow

Faculty Sponsor

Bruce Hrivnak


Arts and Sciences


Physics and Astronomy

Presentation Type

Poster Presentation

Symposium Date

Summer 7-23-2021


My research focuses on finding periodicity in the light variations of a sample of proto-planetary nebulae (PPNe). Proto-planetary nebulae are stars late in their evolution, when they are in transition between the red giant and the planetary nebulae phases. These come from stars like the sun. Analysis of data shows that these objects periodically pulsate, and some have been found to have multiple periods to their pulsation. The main goal is to find pulsation periods for these PPNe, in order to better understand their internal properties. This research was overseen by Dr. Bruce Hrivnak. I am studying two different groups of PPNe. The first group of four has shown evidence of long-term, multi-year variations in previous preliminary studies, and we want to do a complete analysis of their light curves to determine both the pulsation periods and the multi-year periods simultaneously. For example, one has a pulsation period of 103 days and a long-term period of ~3.5 years. The second group are new, previously unstudied PPNe. I am using light curve data from the publicly-available All-Sky Automated Survey for Supernovae, and also, in most cases, data obtained at the Valparaiso University Observatory. Analysis is conducted via Period04, a program which searches for periods in a dataset. For those with long-term periodic variations, the cause is likely due to external factors, such as dust or a binary companion. This research is supported by a grant from the Indiana Space Grant Consortium.

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