# An R-process enhanced star in the dwarf galaxy Tucana III

## TL;DR

This study reports the discovery of an $r$-process enhanced star in the ultra-faint dwarf galaxy Tucana III, providing insights into neutron-capture element origins in such low-luminosity systems.

## Contribution

First identification of an $r$-I star in an ultra-faint dwarf galaxy, expanding understanding of $r$-process enrichment in low-mass galaxies.

## Key findings

- The star shows mild $r$-process enhancement with 28 measured elements.
- Tucana III is the second ultra-faint galaxy with $r$-process enriched material.
- Comparison suggests a common origin for neutron-capture elements across systems.

## Abstract

Chemically peculiar stars in dwarf galaxies provide a window for exploring the birth environment of stars with varying chemical enrichment. We present a chemical abundance analysis of the brightest star in the newly discovered ultra-faint dwarf galaxy candidate Tucana III. Because it is particularly bright for a star in an ultra-faint Milky Way satellite, we are able to measure the abundance of 28 elements, including 13 neutron-capture species. This star, DES J235532.66$-$593114.9 (DES J235532), shows a mild enhancement in neutron-capture elements associated with the $r$-process and can be classified as an $r$-I star. DES J235532 is the first $r$-I star to be discovered in an ultra-faint satellite, and Tuc III is the second extremely low-luminosity system found to contain $r$-process enriched material, after Reticulum II. Comparison of the abundance pattern of DES J235532 with $r$-I and $r$-II stars found in other dwarf galaxies and in the Milky Way halo suggests a common astrophysical origin for the neutron-capture elements seen in all $r$-process enhanced stars. We explore both internal and external scenarios for the $r$-process enrichment of Tuc III and show that with abundance patterns for additional stars it should be possible to distinguish between them.