The properties of the relative abundances of rapid and slow neutron-capture elements are studied using a catalog containing spectroscopic abundance determinations for 14Â elements produced in various nuclear-synthesis processes for 90Â open clusters .
The catalog also contains the positions , ages , velocities , and elements of the Galactic orbits of the clusters .
The relative abundances of both r -elements ( Eu ) and s -elements ( Y , Ba , La , and Ce ) in clusters with high , elongated orbits and in field stars of the Galactic thin disk display different dependences on metallicity , age , Galactocentric distance , and the elements of the Galactic orbits , supporting the view that these objects have different natures .
In young clusters , not only barium , but also the three other studied s -elements display significantly higher relative abundances than field stars of the same metallicity .
The relative abundances of Eu are lower in high-metallicity clusters ( { [ Fe / H ] } > -0.1 ) with high , elongated orbits than in field giants , on average , while the [ Eu/Fe ] ratios in lower-metallicity clusters are the same as those in field stars , on average , although with a large scatter .
The metallicity dependence of the [ O , Mg/Eu ] ratios in clusters with high , elongated orbits and in field stars are substantially different .
These and other described properties of the Eu abundances , together with the properties of the abundances of primary \alpha -elements , can be understood in a natural way if clusters with high , elongated orbits with different metallicities formed as a result of interactions of two types of high-velocity clouds with the interstellar medium of the Galactic disk : low-metallicity high-velocity clouds that formed from “ primordial ” gas , and high-metallicity clouds with intermediate velocities that formed in “ Galactic fountains ” .