Elemental Abundances of Solar Sibling Candidates

TL;DR

This study identifies and confirms the solar sibling candidate HD162826 through detailed chemical and dynamical analysis, emphasizing the importance of selecting elements with high star-to-star scatter for chemical tagging.

Contribution

The paper provides a comprehensive chemical and dynamical assessment of solar sibling candidates, highlighting the effectiveness of targeted elemental analysis over broad element studies.

Findings

Only two candidates have solar chemical composition.

HD162826 satisfies both chemical and dynamical criteria as a solar sibling.

Chemical tagging benefits from focusing on elements with high star-to-star scatter.

Abstract

Dynamical information along with survey data on metallicity and in some cases age have been used recently by some authors to search for candidates of stars that were born in the cluster where the Sun formed. We have acquired high resolution, high signal-to-noise ratio spectra for 30 of these objects to determine, using detailed elemental abundance analysis, if they could be true solar siblings. Only two of the candidates are found to have solar chemical composition. Updated modeling of the stars' past orbits in a realistic Galactic potential reveals that one of them, HD162826, satisfies both chemical and dynamical conditions for being a sibling of the Sun. Measurements of rare-element abundances for this star further confirm its solar composition, with the only possible exception of Sm. Analysis of long-term high-precision radial velocity data rules out the presence of hot Jupiters and confirms that this star is not in a binary system. We find that chemical tagging does not necessarily benefit from studying as many elements as possible, but instead from identifying and carefully measuring the abundances of those elements which show large star-to-star scatter at a given metallicity. Future searches employing data products from ongoing massive astrometric and spectroscopic surveys can be optimized by acknowledging this fact.