Abstract:
High-resolution optical spectroscopy was conducted for the metal-poor post-AGB star
CC Lyr to determine its chemical abundances and spectral line profiles. Our standard
abundance analysis confirms its extremely low metallicity ([Fe
/
H]
<
−
3.5) and a clear
correlation between abundance ratios and the condensation temperature for 11 elements,
indicating that dust depletion is the cause of the abundance anomaly of this object.
The very low abundances of Sr and Ba, which are detected for the first time for this
object, suggest that heavy neutron-capture elements are not significantly enhanced in
this object by the s-process during its evolution through the AGB phase. The radial
velocity of this object and profiles of some atomic absorption lines show variations
depending on pulsation phases, which could be formed by dynamics of the atmosphere
rather than by binarity or contributions of circumstellar absorption. On the other hand,
the H
α
emission with double peaks shows no evident velocity shift, suggesting that
the emission is originating from the circumstellar matter, presumably the rotating disk
around the object
