A Chemical Signature from Fast-rotating Low-metallicity Massive Stars: ROA 276 in ω Centauri

Abstract

We present a chemical abundance analysis of a metal-poor star, ROA 276, in the stellar system ω Centauri. We confirm that this star has an unusually high [Sr/Ba] abundance ratio. Additionally, ROA 276 exhibits remarkably high abundance ratios, [X/Fe], for all elements from Cu to Mo along with normal abundance ratios for the elements from Ba to Pb. The chemical abundance pattern of ROA 276, relative to a primordial ω Cen star ROA 46, is best fit by a fast-rotating low-metallicity massive stellar model of 20 M, [Fe/H] = −1.8, and an initial rotation 0.4 times the critical value; no other nucleosynthetic source can match the neutron-capture element distribution. ROA 276 arguably offers the most definitive proof to date that fast-rotating massive stars contributed to the production of heavy elements in the early universe