Abundance Analysis and Origin of the Zeta Sculptoris Open Cluster

Abstract

We have determined chemical abundances and radial velocities for stars in the field of the zeta Sculptoris cluster. We find that the cluster metal deficiency previously found from UBV photometry is too high; the cluster overall metallicity, [Fe/H]=+0.24, is about 70% higher than the solar value. The chemical abundance pattern is unusual: the Ni/Fe ratio is significantly lower than typical for field stars with similar Fe and Ca abundances, and the cluster may also be deficient in the alpha element Si. For its age, the cluster is unusually far from the galactic disk, approximately 240 pc. The adopted heliocentric cluster radial velocity, +3.9 km/s, shows that it is close to its maximum distance from the galactic plane. We suggest that the zeta Sculptoris cluster was formed in the galactic disk 45 Myr ago by the interaction of a high velocity cloud with the interstellar medium, and that its formation may be connected with that of Gould's Belt. (Table3, postscript figures and text available by anonymous ftp from "chiron.astro.uu.se" in directory pub/articles/atmos/P90)