Period Study of Post-Red Giant Stars

Primary Submission Contact

Stephen Freund

Faculty Sponsor

Dr. Bruce Hrivnak

Faculty Sponsor Email Address



Arts and Sciences



Document Type

Oral Presentation


Fall 9-12-2014


Stars age through time and go through a series of stages. My group’s research involves stars in between the red giant and the white dwarf stages. At the end of the red giant stage, stars begin to shed their outer layers, sometimes forming proto-planetary nebulae, followed by planetary nebulae. These post-red giant stars are known to fluctuate in brightness over time. Our research group observed about 25 of these stars on clear nights during the summer of 2014, using the VU Observatory. We then combined the brightness measurements for these stars, with data collected over the past 20 years at the VU Observatory and searched for periodicity in the variations. The periods discovered, if any, will be useful for determining the structure of the star and may give hints to the process by which these stars shed their outer layers. I made a detailed study of two post-red giant stars, IRAS 19114+0002 and IRAS 20004+2955, and found primary and secondary periods for each, ranging from 142 to 270 days. I thank my mentors in this project, Prof. Bruce Hrivnak and Mr. Wen Lu. I acknowledge the support of the National Science Foundation and NASA though the Indiana Space Grant Consortium, in addition to VU.

Biographical Information about Author(s)

Stephen is a Junior physics major with plans to go to grad school for condensed matter physics after graduation,

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