Abundance Analyses of Field RV Tauri Variables. III. DY Aquilae, SS Geminorum, CT Orionis, and CE Virginis

Analyses of the photospheric compositions of the four field RV Tauri stars, DY Aql, SS Gem, CT Ori, and CE Vir, indicate that to varying degrees they have experienced fractionation processes that have preferentially depleted their atmospheres of elements with high condensation temperatures. This corroborates our previous studies, which showed similar patterns in five other field RV Tauri stars. Two stars in our sample, DY Aql and CE Vir, were found to have strong Li I resonance lines, with corresponding lithium abundances near log (Li) = 0.0; this is not significantly different from that found in less evolved M giants. These are also the coolest stars displaying a correlation of photospheric abundances with condensation temperatures.