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Title: The lowest detected stellar Fe abundance: the halo star SMSS J160540.18−144323.1
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 $$\left[\rm {Fe}/\rm {H}\right]= -6.2 \pm 0.2$$ (1D LTE), the lowest ever detected abundance of iron in a star. The star is strongly carbon-enhanced, $$\left[\rm {C}/\rm {Fe}\right] = 3.9 \pm 0.2$$, while other abundances are compatible with an α-enhanced solar-like pattern with $$\left[\rm {Ca}/\rm {Fe}\right] = 0.4 \pm 0.2$$, $$\left[\rm {Mg}/\rm {Fe}\right] = 0.6 \pm 0.2$$, $$\left[\rm {Ti}/\rm {Fe}\right] = 0.8 \pm 0.2$$, and no significant s- or r-process enrichment, $$\left[\rm {Sr}/\rm {Fe}\right] \lt 0.2$$ and $$\left[\rm {Ba}/\rm {Fe}\right] \lt 1.0$$ (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 $$10\, \rm M_\odot$$ imparting a low kinetic energy on the supernova ejecta, while models for stars more massive than roughly $$20\, \rm M_\odot$$ are incompatible with the observed abundance pattern.  more » « less
Award ID(s):
1716251
PAR ID:
10198211
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ;
Date Published:
Journal Name:
Monthly Notices of the Royal Astronomical Society: Letters
Volume:
488
Issue:
1
ISSN:
1745-3925
Page Range / eLocation ID:
L109 to L113
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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