A Long Term Study of 89 Her: A Semi-Regular Pulsating Star

Faculty Sponsor

Bruce Hrivnak


Arts and Sciences


Department of Physics and Astronomy

ORCID Identifier(s)


Document Type

Poster Presentation

Symposium Date

Summer 7-28-2015


Beginning in 1994, the astronomy research group at Valparaiso University has been studying the light curves of Proto-Planetary Nebulae (PPNe). In addition, we have also have been studying a few stars with similar properties. For one of these stars, 89 Her, a semi-regular pulsating binary star, we have been collecting brightness data since 1994 and have continued to do so up to the present time. These data were combined with data published Fernie in order to look for periodicity in the data. In addition to that, we combined radial velocity data from a collaborator in Canada with data published Waters in order to find periodicity. The periods found can be used to determine some of the properties of the star. From the brightness data in the R and V filters, I have determined one period of approximately 283 days in both V and R, a second period of 76.6 days in R and 65 days in the V, and a third period of 67 days in the V. From the radial velocity data, I have determined one dominant period of 290 days and two additional periods of 65 days and 61 days respectively. The longer period of approximately 283 days is thought to be due to light variation from the binary system. The shorter periods ranging from 60-80 days are due to the expanding and contracting of the main star. This research is supported by grants from the NSF and from NASA through the Indiana Space Grant Consortium.

Biographical Information about Author(s)

I am going to be a junior at Valparaiso University. I am a physics major who is currently Premed. This is my second year working on this project.

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