Mn, Cu and Zn abundances in barium stars and their correlations with neutron capture elements

TL;DR

This study analyzes Mn, Cu, Zn, and neutron capture element abundances in barium and normal giant stars, revealing correlations and suggesting different nucleosynthesis origins for these elements.

Contribution

It provides new abundance measurements and explores correlations between elements, highlighting the roles of various stellar processes in element synthesis.

Findings

[Zn/Fe] correlates with heavy element excesses, increasing with their abundance.

[Cu/Fe] and [Mn/Fe] do not show the same correlation trend.

Mn is mainly produced by SN Ia, while Zn and Cu have contributions from massive stars and the weak s-process.

Abstract

We present abundances of Mn, Cu, Zn and various light and heavy elements for a sample of barium and normal giant stars, and present correlations between abundances contributed to different degrees by the weak-s, main-s, and r-processes of neutron capture, between Fe-peak elements and heavy elements. Data from the literature are also considered in order to better study the abundance pattern of peculiar stars. The stellar spectra were observed with FEROS/ESO, and the stellar atmospheric parameters of the 8 barium giant stars and 6 normal giants analyzed by us lie in the range 4300 < T_eff/K < 5300, -0.7 < [Fe/H] <= 0.12 and 1.5 <= log g < 2.9. Carbon and nitrogen abundances were derived by the spectral synthesis of molecular bands of C_2, CH and CN. For all the other elements, atomic lines were used to perform the spectral synthesis. A very large scatter was found when data from the literature were considered, mainly for the Mn abundances. We found that [Zn/Fe] correlates well with the heavy element excesses, its abundance clearly increasing as the heavy element excesses increase, a trend not shown by the [Cu/Fe] and [Mn/Fe] ratios. Also, the excess of Mn, Cu and Zn relative to heavy elements usually show an increasing trend toward higher metallicities. Our results suggest that a larger fraction of the synthesis of Zn is owed to massive stars than is the case of Cu, and that the contribution of the main-s process to the synthesis of both elements is small. We also conclude that Mn is mostly synthesized by SN Ia, and that a non-negligible fraction of the synthesis of Mn, Cu and Zn is owed to the weak s-process.