2019 publications | All publications
SkyMapper Publication
The lowest detected stellar Fe abundance: The halo star SMSS J160540.18-144323.1
Nordlander, T. et al., 2019, Monthly Notices of the Royal Astronomical Society, L112 | View on ADS (2019MNRAS.tmpL.112N)
Abstract
We report the discovery of SMSS J160540.18-144323.1, a new ultra-metal poor halo star discovered with the SkyMapper telescope. We measure [Fe/H] = -6.2 ± 0.2 (1D LTE), the lowest ever detected abundance of iron in a star. The star is strongly carbon-enhanced, [C/Fe] = 3.9 ± 0.2, while other abundances are compatible with an α-enhanced solar-like pattern with [Ca/Fe] = 0.4 ± 0.2, [Mg/Fe] = 0.6 ± 0.2, [Ti/Fe] = 0.8 ± 0.2, and no significant s- or r-process enrichment, [Sr/Fe] < 0.2 and [Ba/Fe] < 1.0 (3σ limits). Population III stars exploding as fallback supernovae may explain both the strong carbon enhancement and the apparent lack of enhancement of odd-Z and neutron-capture element abundances. Grids of supernova models computed for metal-free progenitor stars yield good matches for stars of about 10 M☉ imparting a low kinetic energy on the supernova ejecta, while models for stars more massive than roughly 20 M☉ are incompatible with the observed abundance pattern.
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