Period Changes in Pulsating Red Supergiant Stars: A Science and Education Project

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John R. Percy
Elena Favaro
Jou Glasheen
Bernadette Ho
Hiromitsu Sato

Department of Astronomy and Astrophysics, University of Toronto, Toronto ON Canada M5S 3H4

David G. Turner

Department of Astronomy and Physics, Saint Mary's University, Halifax NS B3H 3C3


Based on a paper presented at the 96th Fall Meeting of the AAVSO, Cambridge MA, November 3, 2007.

Received February 22, 2008; accepted March 26, 2008



We describe research done as part of the University of Toronto Mentorship Program, which enables outstanding senior high school students to work on research projects at the university. The students began with extensive background reading on variable stars, and became familiar with various forms of time-series analysis by applying them to a few red supergiant variables in the AAVSO International Database; we report on the results. They also prepared a useful manual for our publicly-available self-correlation analysis software. They undertook an intensive analysis of the period changes in BC Cyg, using the AAVSO and Turner data and the (O-C) method, in the hope that evolutionary period changes could be observed. The (O-C) diagram, however, is dominated by errors in determining the times of maximum, and by the effects of cycle-to-cycle period fluctuations. As a result, the (O-C) method is generally not effective for these stars. We also describe the Mentorship Program and its elements, and reflect on the students' experience.

Link to article on ADS