# Detailed chemical composition and orbit of the new globular cluster FSR1758: Implications for the accretion of the Sequoia dwarf galaxy onto the Milky Way

## TL;DR

This study provides detailed chemical, kinematic, and orbital data for the globular cluster FSR 1758, supporting its classification as a Milky Way halo cluster with a retrograde, eccentric orbit, and discussing implications for the accretion of the Sequoia dwarf galaxy.

## Contribution

It offers the first high-resolution spectroscopic analysis of FSR 1758, confirming its metallicity, chemical abundance patterns, and orbital parameters, and discusses its origin and relation to galaxy accretion events.

## Key findings

- Metallicity of [Fe/H] = -1.58 with small spread.
- Cluster exhibits Na-O anti-correlations typical of Milky Way halo globulars.
- Retrograde, highly eccentric orbit confirmed.

## Abstract

We present detailed chemical abundances, radial velocities and orbital parameters for FSR 1758, a recently discovered star cluster in the direction of the Galactic Bulge. High resolution (R~42,000) spectra were obtained using the Magellan/Clay telescope instrumented with MIKE echelle spectrogragh, wavelength range 4900-8700 \AA. Cluster membership was determined using Gaia DR2 proper motions and confirmed with our radial velocity measurements. We find metallicity consistent with previous photometric estimates for this cluster, [Fe/H] = -1.58+-0.03 dex, with a small, 0.08 dex, spread. While other studies have suggested this massive object may be the result of a previous accretion event, our results are consistent with Milky Way Halo globular clusters with characteristic Na-O anti-correlations found for the metal-poor cluster members. The mean radial velocity of the cluster, +226.8+-1.6 km/s with a small velocity dispersion, 4.9+-1.2 km/s, is typical for globular clusters. We also confirm a retrograde Galactic orbit that appears to be highly eccentric.