Cepheid radial abundance gradients

To this end, we observed objects in a wide range of Galactocentric radii, allowing us to study in detail the abundance gradients present in the Galactic disc. We present the results of the analysis of 331 spectra obtained for 180 individual DCEPs with a variety of high-resolution spectrographs. For each target, we derived accurate atmospheric parameters, radial velocities, and abundances for up to 29 different species.

The iron abundances range between 0.5 and ~1dex with a rather homogeneous distribution in metallicity. Results. The sample presented in this paper was complemented with that already published in the context of the C-MetaLL survey, resulting in a total of 292 pulsators whose spectra have been analysed in a homogeneous way.

These data were used to study the abundance gradients of the Galactic disc in a range of Galactocentric radii (R_GC_) spanning the range 5-20kpc. For most of the elements we found a clear negative gradient, with a slope of ~0.064+/-0.003dex/kpc for [Fe/H] case. Through a qualitative fit with the Galactic spiral arms we shown how our farthest targets (R_GC_>10kpc) trace both the Outer and Outer Scutum-Centaurus arms.

The homogeneity of the sample will be of pivotal importance for the study of the metallicity dependance of the DCEP PL relations.