Analysis of neutron capture elements in metal-poor stars

Abstract

We derived model atmosphere parameters (Teff, log g, [Fe/H], Vt) for 90 metal-deficient stars (-0.5 -1.5, when the matter of the Galaxy is sufficiently homogeneous. The analysis of n-capture element abundances confirms the jump in [Ba/Fe] at [Fe/H]= -2.5. Some stars from our sample at [Fe/H] < -2.5, the essential contribution to the n-rich element abundances derives from the r-process. The main sources of these processes may be low mass SN II. The larger dispersion of s-process element abundances with respect to α-rich elements may arise both from the birth of metal-poor stars in globular clusters with following different evolutionary paths and (or) from differences in s-element enrichment in Galaxy populations.