The Overall Properties of Open Clusters Located Towards The Galactic Anticenter Direction: Washington Photometry of NGC 1817 and NGC 2251

PARISI, M. C.; CLARIÁ, J. J.; PIATTI, A. E.; GEISLER, D.

Pucon - Chile

Congreso; XI IAU Regional Latin American Meeting of Astronomy; 2006

Unión Astronómica Internacional

We present Washington photometry for red giant candidates in the open clusters NGC 1817 and NGC 2251. Coravel radial velocities are used to separate field stars from cluster giants. Effective temperatures and metallicities are derived for each giant star. From new UBV and DDO data, we also derive reddening and metal content for NGC 2251. We find [Fe/H] = -0.33+/-0.08 and -0.20+/-0.05 for NGC 1817 and NGC 2251, respectively. We reexamine the overall properties of a sample of 30 clusters in the Galactic anticenter direction with distances, ages and metallicities available. No evidence for an age-metallicity relation is found. However, a radial abundance gradient of -0.093 dex kpc^{-1} is derived over a Galactocentric distance of 14 kpc. This value practically does not change when all clusters with basic parameters known up to this date are considered.