Long-Term Brightness Study in 89 Her

Primary Submission Contact

Christopher Morrissey

Faculty Sponsor

Bruce Hrivnak

Faculty Sponsor Email Address



Arts and Sciences


Physics and Astronomy

Document Type

Oral Presentation


Fall 9-12-2014


89 Her is a well-known post AGB star or a star that has evolved past the red giant stage of its evolution that has been studied since the 1950s. Over the summer, I combined data collected at Valparaiso University Observatory (VUO) from 1993-2013 with data observed and published in the literature by Fernie beginning in 1986. This combined light curve was used to study the variations in brightness of this star and to search for specific periods in the light curves. By studying the brightness variations, we hope to better understand the internal structure of this particular star. For 89 Her, I have determined one dominant period and one additional period. These periods are 65 and 284 days. These periods correspond s to variation in the brightness of the star itself and the light variation caused by the binary system , respectively. This project is part of a long-term project to monitor the light variations of this star and other post AGB stars. I also helped observe ~25 of these stars at VUO. I would like to thank my mentors in this project, Prof. Bruce Hrivnak and Mr. Wen Lu. This research is supported by grants from the NSF and from NASA through the Indiana Space Grant Consortium, along with Valparaiso University

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