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 AGB phase .
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 \alpha 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 .