Cepheids as tracers of the metallicity gradient across the Galactic disk

Abstract

We present iron abundance measurements, based on high resolution spectroscopy, and accurate distance determinations, based on near infrared photometry, for 34 Galactic Cepheids. The new data are used to constrain the Galactic iron abundance gradient in the outer disk, namely from 10 to 14 kpc. We confirm the flattening of the gradient toward the outer disk. In this region we also found an increase in the metallicity dispersion. Current data do not support the occurrence of a jump in the metallicity gradient for Galactocentric distances of the order of 10-12 kpc.