{alpha}-element abundances of Cepheid stars

The abundances are based on high spectral resolution (R~38000) and high signal-to-noise ratio (S/N~50-300) spectra collected with UVES at ESO VLT. Special attention was given to providing a homogeneous abundance scale for these five elements plus iron.

In addition, accurate Galactocentric distances (RG) based on near-infrared photometry are also available for all the Cepheids in the sample. We found that these five elements display well-defined linear radial gradients and modest standard deviations over the entire range of RG. The [element/Fe] abundance ratios are constant across the entire thin disk and over the entire period range; only the Ca radial distribution shows marginal evidence of slopes.