Lead, Tin, and Germanium in the Small Magellanic Cloud Main‐Sequence B Star AV 304

Abstract

We have determined the lead, tin, and germanium abundances of the early B main-sequence star AV 304 in the Small Magellanic Cloud (SMC) by using archival STIS/HST G140M spectral data to measure the Ge IV 1229.8 Å, Sn IV 1313.5 Å, and Pb IV 1313.1 Å resonance lines. We find [Ge/H] ≈ -1.8, [Sn/H] ≈ -1, and [Pb/H] ≈ -0.15. We argue that finding a nearly solar system lead abundance in a metal-poor SMC star is consistent with both previously measured trends in SMC s-process elements and recent theoretical s-process stellar and chemical evolution models that predict that a large fraction of the lead in our own Galaxy was produced by the s-process in low-mass stars of metallicity [Fe/H] between -1.5 and -1. We have also estimated the isotopic and hyperfine splitting of the Pb IV 1313.1 line and conclude that any uncertainties in the isotopic mixture do not significantly affect the derived lead abundance.