Overabundance of s-process elements in the atmosphere of the active red giant

TL;DR

This study analyzes the atmospheric composition of the active red giant PZ Mon, revealing overabundances of lithium and s-process elements, likely linked to stellar activity and similar processes observed in barium stars.

Contribution

It provides detailed elemental abundances in PZ Mon using high-resolution spectra, accounting for hyperfine splitting and non-LTE effects, highlighting overabundances related to stellar activity.

Findings

Overabundance of lithium in PZ Mon's atmosphere.

Enhanced levels of s-process elements similar to barium stars.

Stellar activity likely causes lithium overabundance.

Abstract

Based on high-resolution (R=60000) spectra taken with the NES spectrograph (the 6-m BTA telescope, the Special Astrophysical Observatory of the Russian Academy of Science), we have determined the abundances of 26 elements, from lithium to europium, in the atmosphere of the active red giant PZ Mon, which belongs to the class of RS CVn variable stars, by the method of model stellar atmospheres. We have taken into account the hyperfine splitting, the isotopic shift, and the departure from local thermodynamic equilibrium. Analysis of our data has revealed an overabundance of lithium and neutron-capture elements compared to normal red giants. For lithium, this is explained by the activity of the star, while the overabundance of s-elements is presumably similar in nature to that in moderate barium stars.