Alison SillsDalessandro, E.E.DalessandroMario CadelanoMayte Alfaro-CuelloJ. M. Diederik Kruijssen2021-02-182021-02-1820191745-3925http://hdl.handle.net/20.500.12386/30451The cluster M54 lies at the centre of the Sagittarius dwarf spheroidal galaxy, and therefore may be the closest example of a nuclear star cluster. Either in-situ star formation, inspiralling globular clusters, or a combination have been invoked to explain the wide variety of stellar sub-populations in nuclear star clusters. Globular clusters are known to exhibit light element variations, which can be identified using the photometric construct called a chromosome map. In this letter, we create chromosome maps for three distinct age-metallicity sub-populations in the vicinity of M54. We find that the old, metal-poor population shows the signature of light element variations, while the young and intermediate-age metal rich populations do not. We conclude that the nucleus of Sagittarius formed through a combination of in-situ star formation and globular cluster accretion. This letter demonstrates that properly constructed chromosome maps of iron-complex globular clusters can provide insight into the formation locations of the different stellar populations.STAMPAenArticle10.1093/mnrasl/slz1492-s2.0-85084306104000516532900014http://arxiv.org/abs/1910.00080v1https://academic.oup.com/mnrasl/article-abstract/490/1/L67/5580282?redirectedFrom=fulltext2019MNRAS.490L..67SFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation