The isotopic mixture of barium in the metal-poor subgiant HD 140283

Abstract

Analyses of the abundances of neutron-capture elements have led to the belief that these elements in metal-poor stars are r-process products with relative abundances closely resembling those found in the Solar system. This picture was challenged by Magain, who found that a pure r-process mix of the barium isotopes was inconsistent with the mix of odd to even barium isotopes derived from analysis of the Ba II line at 4554 ˚ A in the spectrum of the metal-poor subgiant HD 140283. In this paper, we address Magain’s challenge using new high-resolution high signal-to-noise spectra of HD 140283, and find, in contrast to his result, that a solar-like r-process isotopic mixture provides a fair fit to the observed 4554- ˚ A profile.