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

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.