The overall properties of open clusters located towards the galactic anticenter direction: Washington photometry of NGC 1817 and NGC 2251

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

Pucón (Chile)

Congreso; XI Regional Latinoamericana de Astronomía; 2005

Unión Astronómica Internacional y Sociedad chilena de Astronomía

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 the UBV and DDO data, we also derive reddening and metal content for NGC 2251. We find [Fe/H] = -0.33 +/- 0.08 and -0.25 +/- 0.04 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 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 data are considered.