Comprehensive abundance analysis of red giants in the open clusters NGC 752, 1817, 2360 and 2506

We have analysed high-dispersion echelle spectra (R greater than or similar to 50 000) of red giant members for four open clusters to derive abundances for many elements. The spread in temperatures and gravities being very small among the red giants nearly the same stellar lines were employed thereby reducing the random errors. The errors of average abundance for the cluster were generally in the range 0.02-0.07 dex. Our present sample covers Galactocentric distances of 8.3-10.5 kpc. The [Fe/H] values are -0.02 +/- 0.05 for NGC 752, -0.07 +/- 0.06 for NGC 2360, -0.11 +/- 0.05 for NGC 1817 and -0.19 +/- 0.06 for NGC 2506. Abundances relative to Fe for elements from Na to Eu are equal within measurement uncertainties to published abundances for thin-disc giants in the field. This supports the view that field stars come from disrupted open clusters.