ABUNDANCES OF RED GIANTS IN OLD OPEN CLUSTERS. IV. NGC 1817, NGC 1883, NGC 2141, AND NGC 2158

We present an analysis of high-dispersion echelle spectra of seven giant stars in the similar to 1-2 Gyr old open clusters NGC 1817, NGC 1883, NGC 2141, and NGC 2158. Abundances were determined relative to the bright, mildly metal-poor disk giant Arcturus. NGC 1817, NGC 1883, NGC 2141, and NGC 2158 are found to have a mean [Fe/H] = -0.07 +/- 0.04, -0.01 +/- 0.01, +0.00 +/- 0.16, and -0.03 +/- 0.14 (s.d.), respectively. All four clusters show modest (similar to 0.1 dex) enhancements of Na and Si, and scaled solar abundances of Al and Mg, while [O/Fe] similar to -0.15 dex. [Ca/Fe] and [Ti/Fe] values are slightly subsolar in all four clusters, but this may be due to a systematic effect. Given that all four of these clusters are located at R-gc > 10 kpc in the disk, and barring any systematic effects, our results imply that any abrupt transition in abundance in the Galactic disk occurs beyond R-gc similar to 13 kpc.