AAS 203rd Meeting, January 2004
Session 8 Delta Scuti and Mira Variables
Poster, Monday, January 5, 2004, 9:20am-6:30pm, Grand Hall

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[8.03] Multiple-Wavelength Monitoring of Mira-Type Stars for Microvariability

W. K. Teets (Austin Peay State University), G. D. Henson (East Tennessee State University)

We report here on synoptic observations being carried out on a sample of Mira stars for which short-term brightness variations were reported by De Laverny et al. (1998, A & A) from HIPPARCOS data. Initial pilot observations during summer 2001 of one star (RR Boo, see Guenther and Henson 2001, B.A.A.S.) detected a large amplitude event which tended to confirm the de Laverny et al. findings. We began an intensive monitoring program in order to detect as many events as possible to establish their characteristics and their connection, if any, to the long-term pulsation cycles of these stars. CCD photometry in B, V, R, and I filters was performed on all stars with some stars also observed with a subset of Wing filters (1992, J. AAVSO). The observations were typically carried out over several consecutive nights with up to five data points obtained per hour for up to eight hours. The data now span a period of over two years and sample a significant part of the phase cycle for each star. However, with the exception of the one RR Boo event, we find no significant variations for any star in our sample, at any observed wavelength, for the short time scales observed. Given the sampling frequency of our observations and size of our sample, the implications of our non-detection concerning the presence of any microvariability in Mira stars is discussed. This work has been supported by NSF grant AST-0097616 for the Southeastern Association for Astronomical Research (SARA) Research Experiences for Undergraduates program.

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.