A SPECTROSCOPIC AND PHOTOMETRIC STUDY OF THE METAL-POOR, PULSATING, POST-ASYMPTOTIC GIANT BRANCH BINARY HD 46703
- Citation data:
The Astronomical Journal, ISSN: 0004-6256, Vol: 136, Issue: 4, Page: 1557-1565
- Publication Year:
- Physics and Astronomy; Earth and Planetary Sciences; Astrophysics and Astronomy
The metal-poor post-asymptotic giant branch (AGB) star HD 46703 is shown to be a single-line spectroscopic binary with a period of 600 days, a high velocity of -94 km s, and an orbital eccentricity of 0.3. Light-curve studies show that it also pulsates with a period of 29 days. High-resolution, high signal-to-noise spectra were used for a new abundance study. The atmospheric model determined is T= 6250 K, log g = 1.0, V= 3.0 km s, and a metal abundance of [M/H] = -1.5. A low carbon abundance and a lack of s-process element enhancement indicate that the star has not experienced a third dredge-up on the AGB. The sulfur and zinc abundances are high compared with iron, and the chemical abundances show a clear anti-correlation with condensation temperature. The abundance depletion pattern is similar to that seen in other post-AGB binaries, and, like them, is attributed to the chemical fractionation of refractory elements onto dust stored in a circumbinary disk and the re-accretion of volatiles in the stellar atmosphere. The infrared excess is small but the excess energy distribution is very similar to what can be expected from a disk. HD 46703 joins the growing list of depleted, post-AGB stars which are likely surrounded by a dusty and stable circumbinary disk. © 2008. The American Astronomical Society. All rights reserved.