Variability in Post-AGB Stars: Pulsation in Proto-Planetary Nebulae
We have been intensely monitoring photometric variability in proto-planetary nebulae (PPNe) over the past 25 years and radial velocity variability over the past ten years. Pulsational variability has been obvious, in both the light and velocity, although the resulting curves are complex, with multiple periods and varying amplitudes. Observed periods range from 25 to 160 days, and the periods and amplitudes reveal evolutionary trends. We will present our observational results to date for approximately 30 PPNe, and discuss these results, including the search for period changes that might help constrain post-AGB evolutionary timescales.
Hrivnak, Bruce; Henson, Gary; Van De Steene, Griet; Van Winckel, Hans; Hillwig, Todd; and Bremer, Matthew. 2019. Variability in Post-AGB Stars: Pulsation in Proto-Planetary Nebulae. Proceedings of the International Astronomical Union. 423-424. https://doi.org/10.1017/S1743921318006956 ISSN: 1743-9213