ChJAA Vol 2, No 5 (2002) / Zhang

A Statistical Model for Predicting the Average Abundance Patterns of Heavier Elements in Metal-Poor Stars

Bo Zhang, Yan-Xia Zhang, Ji Li, Qiu-He Peng

Abstract

We have collected nearly all the available observed data of the elements from Ba to Dy in halo and disk stars in the metallicity range –4.0 < [Fe/H] < 0.5. Based on the observed data of Ba and Eu, we evaluated the least-squares regressions of [Ba/Fe] on [Fe/H], and [Eu/H] on [Ba/H]. Assuming that the heavy elements (heavier than Ba) are produced by a combination of the main components of s- and r-processes in metal-poor stars, and choosing Ba and Eu as respective representative elements of the main s- and the main r-processes, a statistical model for predicting the Galactic chemical evolution of the heavy elements is presented. With this model, we calculate the mean abundance trends of the heavy elements La, Ce, Pr, Nd, Sm, and Dy with the metallicity. We compare our results with the observed data at various metallicities, showing that the predicted trends are in good agreement with the observed trends, at least for the metallicity range [Fe/H] &geq;–2.5. Finally, we discuss our results and deduce some important information about the Galactic chemical evolution.

Keywords


stars: abundances --- stars: Population II --- Galaxy: evolution --- method: statistical

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