IS THERE A METALLICITY ENHANCEMENT IN PLANET-HOSTING RED GIANTS?

The Penn State/Torun Centre for Astronomy Search for Planets Around Evolved Stars is a high-accuracy radial velocity (RV) survey aiming at planet detection around giant stars. It is based on observations obtained with the 9.2 m Hobby-Eberly Telescope. As proper interpretation of high accuracy RV data for red giants requires complete spectral analysis of targets we perform spectral modeling of all stars included in the survey. Typically, rotation velocities and metallicities are determined in addition to stellar luminosities and temperatures, which allows us to estimate stellar ages and masses. Here we present preliminary results of metallicity studies in our sample. We search for a metallicity dependence similar to that for dwarfs by comparing our results for a sample of 22 giants earlier than K5 showing significant RV variations with a control sample of 58 relatively RV-stable stars.