The Bulge Cluster Origin (BulCO) survey with CRIRES at the ESO-VLT: A chemical screening of the globular cluster NGC 6553

In this paper we present the chemical screening of the stellar population belonging to the globular cluster NGC 6553 in the Galactic bulge. This study has been conducted in the contest of the Bulge Cluster Origin (BulCO) survey, an ESO-VLT Large Program that is currently ongoing with CRIRES in the near-infrared (NIR) domain. This survey is performing an unprecedented chemical screening of 17 stellar systems orbiting the Milky Way bulge, with the aim of unveiling their origin and true nature. Here we present and discuss the abundances of 18 elements produced via distinct nucleosynthetic channels for 14 red giant branch stars belonging to NGC 6553. We found a mean Fe/H = -0.20 ± 0.01 dex, and about solar-scaled iron-peak elements, confirming that this is one of the most metal-rich globular clusters in the Milky Way. We also found X/Fe enhancement of α and several other light elements. Furthermore, we assessed the presence of multiple populations typical of genuine globular clusters from the significant spreads in Na, N, and C, along with an almost vertical Na-O anticorrelation. Finally, by using classical ( α/Fe versus Fe/H ) and newly-defined ( V/Fe and Zn/Fe versus Fe/H ) "chemical DNA tests", we have proven its in situ formation within the Galactic bulge.