Chemodynamic analysis of four $r$-process enhanced stars observed with GTC

TL;DR

This study conducts a detailed abundance analysis of four $r$-process enhanced metal-poor stars observed with GTC, revealing multiple production channels for neutron-capture elements and evidence of stellar accretion events.

Contribution

It provides new detailed abundance measurements of four $r$-process stars and insights into their nucleosynthesis origins and formation histories.

Findings

Detection of 16 light and 20 neutron-capture elements including Th.

Evidence of multiple $r$-process production channels from abundance ratios.

Clues of stellar accretion in two of the studied stars.

Abstract

Here, we delineate a comprehensive abundance analysis of four $r$-process enhanced metal-poor stars observed with HORuS spectrograph on a 10-m class telescope, GTC. The high signal-to-noise ratio at $R \approx 25000$ spectral resolution allowed us to detect 16 light and 20 neutron-capture elements along with Th in two stars. Four of our program stars show signatures of mixing in their atmosphere. Through detailed abundance analysis of four $r$-process enhanced stars together with already identified $r$-process-rich stars in literature, we probe the production sites of neutron-capture elements. The [Zr/Eu] ratio as a function of metallicity shows the evidence of multiple channels for the production of $r$-process. Thorium to first and second $r$-process peak elements ratios also support the similar non-universality of neutron-capture elements. An increased sample of $r$-process enhanced stars will enable us understand different formation channels of neutron capture elements. Using the kinematic analysis, we found the clues of accretion for two of our program stars.