Barium Abundances in Cepheids
  We derived the barium atmospheric abundances for a large sample of Cepheids,
comprising 270 stars. The sample covers a large range of galactocentric
distances, from about 4 to 15 kpc, so that it is appropriated to investigate
the existence of radial barium abundance gradients in the galactic disc. In
fact, this is the first time that such a comprehensive analysis of the
distribution of barium abundances in the galactic disc is carried out. As a
result, we conclude that the Ba abundance distribution can be characterized by
a zero gradient. This result is compared with derived gradients for other
elements, and some reasons are briefly discussed for the independence of the
barium abundances upon galactocentric distances.
