The Abundance Origin Of A Highly r-process-Enhanced r-II Star: LAMOST J020623.21+494127.9

TL;DR

This study analyzes the chemical composition of the r-II star LAMOST J020623.21+494127.9, revealing its heavy elements are produced by the main r-process, but with indications of a potentially different r-process pattern.

Contribution

It provides detailed abundance analysis of a highly r-process-enhanced star and explores the astrophysical origins of its elements, suggesting the existence of a different main r-process pattern.

Findings

Heavy neutron-capture elements are produced by the main r-process.

Massive stars significantly contributed to light element production.

The current main r-process model does not fully fit the observed data.

Abstract

Object LAMOST J020623.21+494127.9 (program star) in the thin disk of the Milky Way (MW) is reported as a highly r-process-enhanced (RPE) r-II star with[Eu/Fe]= +1.32 and [Fe/H]= -0.54. The chemical profile of the star reflects the intrinsic composition of the gas cloud present at its birth. Using an abundance decomposition method, we fit 25 elements from the abundance dataset, including 10 heavy neutron capture elements. We explore the astrophysical origin of the elements in this star through its abundance ratios and component ratios. We find that the contributions from the massive stars played a significant role in the production of light elements in the program star. Our analysis reveals that the heavy neutron-capture elements are produced purely by the main r-process. However, the adopted main r-process model does not adequately fit the observed data, suggesting another main r-process pattern may exist.