The lowest detected stellar Fe abundance: The halo star SMSS J160540.18-144323.1. (arXiv:1904.07471v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Nordlander_T/0/1/0/all/0/1">T. Nordlander</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bessell_M/0/1/0/all/0/1">M.S. Bessell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Costa_G/0/1/0/all/0/1">G.S. Da Costa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mackey_A/0/1/0/all/0/1">A.D. Mackey</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Asplund_M/0/1/0/all/0/1">M. Asplund</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Casey_A/0/1/0/all/0/1">A.R. Casey</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chiti_A/0/1/0/all/0/1">A. Chiti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ezzeddine_R/0/1/0/all/0/1">R. Ezzeddine</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Frebel_A/0/1/0/all/0/1">A. Frebel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lind_K/0/1/0/all/0/1">K. Lind</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marino_A/0/1/0/all/0/1">A.F. Marino</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Murphy_S/0/1/0/all/0/1">S.J. Murphy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Norris_J/0/1/0/all/0/1">J.E. Norris</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schmidt_B/0/1/0/all/0/1">B.P. Schmidt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yong_D/0/1/0/all/0/1">D. Yong</a>
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 solar mass imparting
a low kinetic energy on the supernova ejecta, while models for stars more
massive than roughly 20 solar mass are incompatible with the observed abundance
pattern.
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 solar mass imparting
a low kinetic energy on the supernova ejecta, while models for stars more
massive than roughly 20 solar mass are incompatible with the observed abundance
pattern.
http://arxiv.org/icons/sfx.gif
