Studies of classical barium stars

Abstract

Using atmosphere models based on high-resolution spectra, we have derived the abundances of chemical elements in the atmospheres of seven classical barium stars and compared them with the elemental abundances of moderate barium stars and normal red giants. The behavior of elements up to the iron peak is the same in all three groups of giants, providing evidence that they have a common origin. The dependence of the anomalous abundances of s-process elements on stellar mass and metallicity is qualitatively similar for all three groups, probably indicating that a substantial role is played by the evolutionary phase of the stars. We conclude that the barium-star phenomenon and the overabundances of s-process elements in barium stars cannot be explained as a consequence of binarity alone. The extent to which the s-process elements are overabundant is affected by the mass, metallicity, and evolutionary phase of the given star, and any of these parameters may prove to be important in a specific object.