Nucleosynthesis in a Primordial Supernova: Carbon and Oxygen Abundances in SMSS J031300.36-670839.31

TL;DR

This study analyzes the chemical composition of a primordial star, revealing its formation from a supernova with extremely low iron content and providing insights into early universe nucleosynthesis.

Contribution

It presents new spectroscopic data and analysis of a metal-poor star, offering evidence for nucleosynthesis in Population III supernovae with unprecedentedly low iron abundance.

Findings

Oxygen to carbon ratio is approximately 0.02.

Iron abundance limit is less than -7.52 in [Fe/H].

Supports the hypothesis of star formation from Population III supernova ejecta.

Abstract

SMSS J031300.36-670839.3 (hereafter SM0313-6708) is a sub-giant halo star, with no detectable Fe lines and large overabundances of C and Mg relative to Ca. We obtained VLT-UVES spectra extending to 3060 Angstroms showing strong OH A-X band lines enabling an oxygen abundance to be derived. The OH A-X band lines in SM0313-6708 are much stronger than the CH C-X band lines. Spectrum synthesis fits indicate an [O/C] ratio of 0.02 +- 0.175. Our high S/N UVES data also enabled us to lower the Fe abundance limit to [Fe/H]{3D},NLTE < -7.52 (3 sigma). These data support our previous suggestion that the star formed from the iron-poor ejecta of a single massive star Population III supernova.