Peculiarities of Abundances of Selected Elements in Metal-Rich Field RR Lyrae Stars

TL;DR

This study investigates the unusual elemental abundance patterns in metal-rich RR Lyrae stars, revealing lower scandium, titanium, and yttrium levels compared to similar field stars, and discusses potential causes for these anomalies.

Contribution

It provides the first extended spectroscopic catalog analysis showing peculiar elemental abundances in metal-rich RR Lyrae stars and explores possible explanations for these anomalies.

Findings

Metal-rich RR Lyrae stars have lower scandium, titanium, and yttrium abundances.

No europium, zirconium, and lanthanum data available for these stars.

Potential causes for abundance peculiarities are discussed.

Abstract

We use the data of our extended catalog of spectroscopic determinations of elemental abundances in the atmospheres of Galactic-field RR Lyrae type variables to show that metal-rich RR Lyraes ($\rm{[Fe/H]} > -1.0$) have anomalous abundances of some elements. In particular, the relative abundances of scandium, titanium, and yttrium in metal-rich RR Lyrae type variables are lower than the corresponding abundances in field stars of similar metallicity beyond the errors. We discuss the errors of the determination of the abundances of the above elements and point out the fact that no europium, zirconium, and lanthanum abundance determinations are available for metal-rich RR Lyrae type variables. We also analyze various possible causes of the observed peculiarities of the chemical composition of metal-rich RR Lyrae type variables.