SD 1313–0019: ANOTHER SECOND-GENERATION STAR WITH [Fe/H] = −5.0, OBSERVED WITH THE MAGELLAN TELESCOPE
Author(s)Chiti, Anirudh; Jacobson, Heather R.; Placco, Vinicius M.; Frebel, Anna L.; Ji, Alexander Pung
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We present a Magellan/MIKE high-resolution (R ~ 35,000) spectrum of the ancient star SD 1313−0019, which has an iron abundance of [Fe/H] = -5.0, paired with a carbon enhancement of [C/Fe] ~ 3.0. The star was initially identified by Allende Prieto et al. in the BOSS survey. Its medium-resolution spectrum suggested a higher metallicity of [Fe/H] = -4.3 due to the Ca ii K line blending with a CH feature, which is a common issue related to the search for the most iron-poor stars. This star joins several other similar stars with [Fe/H] ≲ -5.0 that all display a combination of low-iron and high-carbon abundances. Other elemental abundances of SD 1313−0019 follow that of more metal-rich halo stars. Fitting the abundance pattern with yields of Population III supernovae suggests that SD 1313−0019 had only one massive progenitor star with 20-30 M[subscript ʘ] that must have undergone a mixing and fallback episode. Overall, there are now five stars known with [Fe/H] ≲ -5.0 (1D local thermodynamic equilibrium abundances). This ever-increasing population of carbon-rich, iron-deficient stars can potentially constrain nucleosynthesis in Population III stars and their supernova explosions, the formation mechanisms of the first low-mass stars, and the nature of the first galaxies.
DepartmentKavli Institute for Astrophysics and Space Research; Massachusetts Institute of Technology. Department of Physics
The Astrophysical Journal. Letters
Frebel, Anna, Anirudh Chiti, Alexander P. Ji, Heather R. Jacobson, and Vinicius M. Placco. “SD 1313–0019: ANOTHER SECOND-GENERATION STAR WITH [Fe/H] = −5.0, OBSERVED WITH THE MAGELLAN TELESCOPE.” The Astrophysical Journal 810, no. 2 (September 9, 2015): L27. © 2015 The American Astronomical Society
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