Abundance analysis of symbiotic stars
J. Mikolajewska¹, M. Gromadzki¹, K.H. Hinkle^2
1 Copernicus Astronomical Center, Warsaw, Poland
² National Optical Astronomy Observatory, Tucson, USA
We will present first results of a detailed abundance analysis of a sample of over 30 symbiotic stars based on high-resolution, near-infrared spectra obtained with the Phoenix spectrometer on Gemini South telescope, the method of standard LTE analysis and atmosphere models, and spectrum synthesis. Symbiotic stars are interacting binaries with a cool red giant primary and a hot white dwarf secondary. It is generally believed that the symbiotic appearance and activity is triggered by high mass loss rate for the giant, possibly due to its enhanced metallicity.

The photospheric abundances for the symbiotic giants will allow for the first time to address properly the role of metallicity in the symbiotic phenomenon. Thus far the only available chemical abundances for these objects are the CNO ratios based on nebular emission lines, and they are best fitted by normal red giants. However, a comparison of these ratios with our first photosperic abundances for the giant in CH Cyg reveals significant differences in C/N and O/N between the two methods.

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