  Barium stars show enhanced abundances of the slow neutron capture (s-process)
heavy elements, and for this reason they are suitable objects for the study of
s-process elements. The aim of this work is to quantify the contributions of
the s-, r- and p-processes for the total abundance of heavy elements from
abundances derived for a sample of 26 barium stars. The abundance ratios
between these processes and neutron exposures were studied. The abundances of
the sample stars were compared to those of normal stars thus identifying the
fraction relative to the s-process main component. The fittings of the sigmaN
curves (neutron capture cross section times abundance, plotted against atomic
mass number) for the sample stars suggest that the material from the companion
asymptotic giant branch star had approximately the solar isotopic composition
as concerns fractions of abundances relative to the s-process main component.
The abundance ratios of heavy elements, hs, ls and s and the computed neutron
exposure are similar to those of post-AGB stars. For some sample stars, an
exponential neutron exposure fits well the observed data, whereas for others, a
single neutron exposure provides a better fit. The comparison between barium
and AGB stars supports the hypothesis of binarity for the barium star
formation. Abundances of r-elements that are part of the s-process path in
barium stars are usually higher than those in normal stars,and for this reason,
barium stars seemed to be also enriched in r-elements, although in a lower
degree than s-elements. No dependence on luminosity classes was found in the
abundance ratios behaviour among the dwarfs and giants of the sample barium
stars.
