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- Nordlander, T., et al.
(författare)
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The lowest detected stellar Fe abundance : the halo star SMSS J160540.18-144323.1
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966 .- 1745-3925 .- 1745-3933. ; 488:1, s. L109-L113
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Tidskriftsartikel (refereegranskat)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 alpha-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 (3 sigma 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 circle dot imparting a low kinetic energy on the supernova ejecta, while models for stars more massive than roughly 20 M circle dot are incompatible with the observed abundance pattern.
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