Metal abundances of red clump stars in open clusters. I. NGC 68191

We present an analysis of high-dispersion spectra (R similar to 40,000) of three red clump stars in the old open cluster NGC 6819. The spectra were ob tained with SARG, the high-dispersion spectrograph of the Telescopio Nazion ale Galileo. The spectra were analyzed using both equivalent widths measure d with an automatic procedure and comparisons with synthetic spectra. NGC 6 819 is found to be slightly metal-rich ([Fe/H] = +0.09 +/- 0.03, internal e rror); there are no previous high-resolution studies to compare. Most eleme nt-to-element abundance ratios are close to solar; we find a slight excess of Si and a significant Na overabundance. Our spectra can also be used to d erive the interstellar reddening toward the cluster by comparing the observ ed colors with those expected from line excitation : we derive E(B-V) = 0.1 4 +/- 0.04, in agreement with the most recent estimate for this cluster.