Cepheids as tracers of the metallicity gradient across the Galactic disk

TL;DR

This study uses high-resolution spectroscopy and near-infrared photometry of 34 Galactic Cepheids to analyze the metallicity gradient across the outer disk, confirming its flattening and increased dispersion beyond 10 kpc.

Contribution

It provides new measurements of iron abundance and distances for Cepheids, constraining the metallicity gradient in the outer Galactic disk and clarifying its behavior.

Findings

Confirmed flattening of the metallicity gradient beyond 10 kpc

Observed increased metallicity dispersion in the outer disk

No evidence for a metallicity jump at 10-12 kpc

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.