Spectroscopic and Photometric Variability of Three Oxygen Rich Post-AGB “Shell” Objects
Document Type
Article
Publication Date
2018
Journal Title
Galaxies
Volume
6
Issue
131
Abstract
Light, color, and radial velocity data (2007–2015) for HD 161796, V887 Her, and HD 331319, three oxygen-rich post-AGB stars, have thus far not provided direct support for the binary hypothesis to explain the shapes of planetary nebulae and severely constrain the properties of any such undetected companions. The light and velocity curves are complex, showing similar periods and variable amplitudes. Nevertheless, over limited time intervals, we compared the phasing of each. The color curves appear to peak with or slightly after the light curves, while the radial velocity curves peak about a quarter of a cycle before the light curves. Thus it appears that these post-AGB stars are brightest when smallest and hottest. The spectra of these objects are highly variable. The Hα line has multiple, variable emission and absorption components. In these oxygen-rich post-AGB stars atmospheric lines, such as near-infrared Ca II triplet and low-excitation atomic lines, also have multiple components and sometimes show line doubling, indicative of shocks induced by pulsation.
Recommended Citation
Van de Steene, Griet C.; Hrivnak, Bruce J.; Van Winckel, Hans; Sperauskas, Julius; and Bohlender, David, "Spectroscopic and Photometric Variability of Three Oxygen Rich Post-AGB “Shell” Objects" (2018). Physics and Astronomy Faculty Publications. 177.
https://scholar.valpo.edu/phys_astro_fac_pub/177
