The solar photospheric abundance of zirconium

TL;DR

This study determines the solar photospheric zirconium abundance using 3D hydrodynamical models and spectral line analysis, highlighting the reliability of Zr II lines over Zr I lines due to blending issues.

Contribution

It provides a new, precise measurement of the solar zirconium abundance using advanced 3D modeling and careful spectral line selection, improving upon previous estimates.

Findings

Zr II lines are reliable indicators for abundance determination.

The derived zirconium abundance is A(Zr)=2.62±0.06.

Neutral zirconium lines are too blended and weak for accurate analysis.

Abstract

Zirconium (Zr), together with strontium and yttrium, is an important element in the understanding of the Galactic nucleosynthesis. In fact, the triad Sr-Y-Zr constitutes the first peak of s-process elements. Despite its general relevance not many studies of the solar abundance of Zr were conducted. We derive the zirconium abundance in the solar photosphere with the same CO5BOLD hydrodynamical model of the solar atmosphere that we previously used to investigate the abundances of C-N-O. We review the zirconium lines available in the observed solar spectra and select a sample of lines to determine the zirconium abundance, considering lines of neutral and singly ionised zirconium. We apply different line profile fitting strategies for a reliable analysis of Zr lines that are blended by lines of other elements. The abundance obtained from lines of neutral zirconium is very uncertain because these lines are commonly blended and weak in the solar spectrum. However, we believe that some lines of ionised zirconium are reliable abundance indicators. Restricting the set to Zr II lines, from the CO5BOLD 3D model atmosphere we derive A(Zr)=2.62+/-0.06, where the quoted error is the RMS line-to-line scatter.