The enigmatic globular cluster UKS 1 obscured by the bulge: H-band discovery of nitrogen-enhanced stars

FERNÁNDEZ-TRINCADO, J. G; MINNITI, D.; BEERS, T.; VILLANOVA, S.; GEISLER, D.; SOUZA, S.; SMITH, L. C.; PLACCO, V. M.; VIEIRA, K.; PÉREZ-VILLEGAS, A.; BARBUY, B.; ALVES-BRITO, A.; MONI BIDIN, C.; ALONSO-GARCÍA, J.; TANG, B.; PALMA, T.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2020 vol. 643

0004-6361

he presence of nitrogen-enriched stars in globular clusters provides key evidence for multiple stellar populations (MPs), as has been demonstrated with globular cluster spectroscopic data towards the bulge, disk, and halo. In this work, we employ the VVV Infrared Astrometric Catalogue (VIRAC) and the DR16 SDSS-IV release of the APOGEE survey to provide the first detailed spectroscopic study of the bulge globular cluster UKS 1. Based on these data, a sample of six selected cluster members was studied. We find the mean metallicity of UKS 1 to be [Fe/H]= −0.98 ± 0.11, considerably more metal-poor than previously reported, and a negligible metallicity scatter, typical of that observed by APOGEE in other Galactic globular clusters. In addition, we find a mean radial velocity of 66.1 ± 12.9 km s−1, which is in good agreement with literature values, within 1σ. By selecting stars in the VIRAC catalogue towards UKS 1, we also measure a mean proper motion of (µα cos(δ