The lowest detected stellar Fe abundance: The halo star SMSS J160540.18-144323.1

T. Nordlander*, M. S. Bessell, G. S. Da Costa, A. D. MacKey, M. Asplund, A. R. Casey, A. Chiti, R. Ezzeddine, A. Frebel, K. Lind, A. F. Marino, S. J. Murphy, J. E. Norris, B. P. Schmidt, D. Yong

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    58 Citations (Scopus)

    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 Hright]= -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 Feright] = 3.9 pm 0.2, while other abundances are compatible with an α-enhanced solar-like pattern with left[rm Ca/rm Feright] = 0.4 pm 0.2, left[rm Mg/rm Feright] = 0.6 pm 0.2, left[rm Ti/rm Feright] = 0.8 pm 0.2, and no significant s- or r-process enrichment, left[rm Sr/rm Feright] lt 0.2 and left[rm Ba/rm Feright] 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.

    Original languageEnglish
    Pages (from-to)L109-L113
    JournalMonthly Notices of the Royal Astronomical Society: Letters
    Volume488
    Issue number1
    DOIs
    Publication statusPublished - 1 Sept 2019

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