High-resolution spectroscopic observations of Hipparcos red clump giants:: Metallicity and mass determinations

We obtain high-resolution and high signal-to-noise ratio spectra of 39 red clump giants selected from the Hipparcos Catalogue. We determine their atmospheric parameters, iron abundances, alpha -element enhancements, and masses. We find that the sample can be divided into a metal-poor group and a metal-rich group. The majority of the stars are metal-rich (Z>0.3 Z(.)) with mass around 2 M-., while the metal-poor group has lower surface gravity and lower mass. The variation of alpha -element abundances with [Fe/H] agrees with that of local G and K disk dwarfs. We also show that the metallicity is weakly correlated with the I-band absolute magnitude and the V-I color, in agreement with Udalski's recent findings. We make the high-resolution spectra available over the internet for interested readers.