Program: GN-2015B-Q-81

The globular cluster Omega Centauri is regarded to be the surviving nucleus of a massive accreted dwarf galaxy. Its defining characteristic are a complex color-magnitude diagram and large abundance variations in iron and s-process elements. It is also now clear that other globular clusters, e.g. M22, exhibit striking similarities to Omega Centauri. The simplest explanation is that these other clusters, with s-process and iron abundance variations, are also surviving nuclei of accreted dwarf galaxies. This hypothesis, if confirmed, has consequences for globular cluster formation, Galactic evolution, and Lambda CDM cosmological models. We propose to study the chemical content of NGC6934, whose color-magnitude diagram is remarkably similar to M22. This study will allow us to confirm if this object is an accreted dwarf galaxy, and constrain their frequency in the Milky Way.