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K. Klinke, B.J. Hrivnak, B. Bucher, K. Cooksey, J. Eaton, N. George, J. Lowry, R. Maupin, K. Musick, C. Pagan, S. Schlobohm, K. Wehmeyer (Valparaiso Univ.)
We studied the light variation of a sample of proto-planetary nebulae candidates. These are objects in transition between the AGB and planetary nebula phases of stellar evolution. This ongoing study includes to date eight years of observations using the 0.4-m telescope and CCD camera at the Valparaiso University Observatory. The objects cover a range in brightness (V=7-13.5) and spectral type (B-K). Almost all of the ~40 PPN candidates studied vary in light, with typical amplitudes of 0.1-0.5 mag. Pulsational periods were found in several, with a range of 25-150 days. However, the light curves do not show a simple form of variability; they appear to have varying amplitudes, varying periods, or likely, multiple periods. The hotter objects varied on a shorter time scale. Light curves from this study will be displayed and the results discussed. These can be used to determine information on the interior structure of these stars. This work was supported by grants from the NSF (9900846) and the Indiana Space Grant Consortium.
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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.