An equatorial ultra iron-poor star identified in BOSS

TL;DR

This paper reports the discovery of an ultra iron-poor star with high carbon abundance, providing insights into early stellar populations and nucleosynthesis through low-resolution spectral analysis.

Contribution

The discovery of a new ultra iron-poor star with high carbon content and analysis of its elemental abundances relative to theoretical models.

Findings

Star has [Fe/H] ~ -4.3 and [C/Fe] ~ +2.5

Abundance ratios are consistent with predictions from metal-free massive stars

Comparison shows deviations in stars with lower [C/Fe] ratios

Abstract

We report the discovery of SDSS J131326.89-001941.4, an ultra iron-poor red giant star ([Fe/H] ~ -4.3) with a very high carbon abundance ([C/Fe]~ +2.5). This object is the fifth star in this rare class, and the combination of a fairly low effective temperature (Teff ~ 5300 K), which enhances line absorption, with its brightness (g=16.9), makes it possible to measure the abundances of calcium, carbon and iron using a low-resolution spectrum from the Sloan Digital Sky Survey. We examine the carbon and iron abundance ratios in this star and other similar objects in the light of predicted yields from metal-free massive stars, and conclude that they are consistent. By way of comparison, stars with similarly low iron abundances but lower carbon-to-iron ratios deviate from the theoretical predictions.