NGC5694: another extra-galactic globular cluster

TL;DR

This study analyzes the chemical composition of six stars in the globular cluster NGC5694, revealing unique abundance patterns that suggest an extra-galactic origin from a dwarf spheroidal galaxy.

Contribution

It provides detailed chemical abundance measurements of NGC5694, highlighting its distinct pattern and proposing its origin from a dwarf galaxy, which is a novel insight.

Findings

NGC5694 has [Fe/H] = -1.83, indicating low metallicity.

The cluster shows solar-scaled [alpha/Fe] ratios.

It has a very low Ba abundance, unlike typical Halo clusters.

Abstract

We discuss the chemical composition of six giant stars of the outer Halo globular cluster NGC5694, through the analysis of UVES@FLAMES high-resolution spectra. The cluster has an average iron content [Fe/H]=--1.83+-0.01, solar-scaled [alpha/Fe] ratios and a very low Ba abundance ([Ba/Fe]=--0.71+-0.06). These anomalous abundance patterns are different from those observed in other Halo globular clusters but similar to those of the metal-poor stars in typical dwarf spheroidal galaxies. These findings suggest an extra-galactic origin for NGC5694, likely from a dwarf spheroidal galaxy.