TY - JOUR
T1 - The lowest detected stellar Fe abundance
T2 - The halo star SMSS J160540.18-144323.1
AU - Nordlander, Thomas
AU - Bessell, Michael Stanley
AU - Da Costa, Gary
AU - Mackey, Dougal
AU - Asplund, Martin
AU - Casey, Andrew
AU - Chiti, Anirudh
AU - Ezzeddine, Rana
AU - Frebel, Anna
AU - Lind, Karin
AU - Marino, Anna F
AU - Murphy, Simon
AU - Norris, John
AU - Schmidt, Brian
AU - Yong, David
PY - 2019/9
Y1 - 2019/9
N2 - 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.
AB - 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.
KW - stars: abundances
KW - stars: individual: SMSS J160540.18-144323.1
KW - stars: Population III
UR - http://www.scopus.com/inward/record.url?scp=85071634178&partnerID=8YFLogxK
U2 - 10.1093/mnrasl/slz109
DO - 10.1093/mnrasl/slz109
M3 - Article
AN - SCOPUS:85071634178
VL - 488
SP - L109-L113
JO - Monthly Notices of the Royal Astronomical Society: Letters
JF - Monthly Notices of the Royal Astronomical Society: Letters
SN - 1745-3925
IS - 1
ER -