Imprints of fast-rotating massive stars in the Galactic Bulge

NGC 6522, the oldest globular cluster in our Galaxy, probably witnessed the earliest phases of the chemical enrichment of the Universe, when massive stars formed soon after the Big Bang generated the 'metals' (elements heavier than helium) that were incorporated into the low-mass stars that have survived to the present. However, reported element abundances in stars from NGC 6522 provided contradictory evidence about the nature of the gas from which they were formed. A reanalysis of the earlier spectra, adding yttrium and strontium abundances and upper limits for carbon, points to a pattern of abundances best explained by the early presence of metal-poor fast-rotating massive stars. These 'spinstars' are prime candidates for recognition as the 'first stars' in the Universe.