High-dispersion sp. of 8 Phoenix stream red giants

In this work we use Magellan/Magellan Inamori Kyocera Echelle (MIKE) high-dispersion spectroscopy of eight Phoenix stream red giants to confirm this scenario. In particular, we find negligible intrinsic scatter in metallicity ({sigma}([FeII/H])=0.04_-0.03_^+0.11^) and a large peak-to-peak range in [Na/Fe] and [Al/Fe] abundance ratios, consistent with the light element abundance patterns seen in the most metal-poor globular clusters.

However, unlike any other globular cluster, we also find an intrinsic spread in [SrII/Fe] spanning ~1dex, while [BaII/Fe] shows nearly no intrinsic spread ({sigma}([BaII/H])=0.03_-0.02_^+0.10^). This abundance signature is best interpreted as slow-neutron-capture element production from a massive fast-rotating metal-poor star (15-20M_{sun}_, v_ini_/v_crit_=0.4, [Fe/H]=-3.8). The low inferred cluster mass suggests the system would have been unable to retain supernovae ejecta, implying that any massive fast-rotating metal-poor star that enriched the interstellar medium must have formed and evolved before the globular cluster formed.