A study of the metal-rich, thick disk globular cluster NGC5927

TL;DR

This study identifies 72 radial velocity member stars in the metal-rich globular cluster NGC5927, providing insights into its stellar population and contamination levels near the Galactic disk.

Contribution

It offers the first comprehensive list of radial velocity members in NGC5927, improving membership determination by combining multi-epoch spectra and velocity analysis.

Findings

Radial velocity of NGC5927 is -104.03 km/s.

50% contamination in outer regions when using position alone.

Clear separation of cluster members from background stars.

Abstract

We present a list of 72 radial velocity member stars in the metal-rich globular cluster NGC5927. The radial velocities are based on multi-epoch, multi-fibre spectra. We identify 46 RGB/HB stars and 26 turn-off stars that are radial velocity members in the cluster. This cluster is situated quite close to the disk and hence fore- and/or background contamination, especially in the outskirts of the cluster, can be quite severe. Fortunately, the cluster has a radial velocity (we determine it to v_rad=--104.03 +/- 5.03 km/s) that sets it clearly apart from the bulk velocities of the surrounding, background, and foreground stellar populations. Hence, our identification of members is clean and we can quantify a 50% contamination when stars in the outer part of the cluster are selected solely based on position in the colour-magnitude diagram as opposed to selections based on radial velocities.