Detection of Phosphorus, Sulphur, and Zinc in the Carbon-Enhanced Metal-Poor Star BD+44 493

TL;DR

This study reports the first detections of phosphorus and sulfur, and a second detection of zinc, in an extremely metal-poor star, providing insights into the star's nucleosynthetic origins and supernova enrichment models.

Contribution

First detection of P and S, and second of Zn, in an extremely metal-poor star, expanding understanding of early star enrichment processes.

Findings

Detected P, S, and Zn in BD+44 493.

Abundance ratios suggest enrichment by a faint supernova.

Excludes dust depletion as cause of observed abundance pattern.

Abstract

The carbon-enhanced metal-poor star BD+44 493 ([Fe/H]=-3.9) has been proposed as a candidate second-generation star enriched by metals from a single Pop III star. We report the first detections of P and S and the second detection of Zn in any extremely metal-poor carbon-enhanced star, using new spectra of BD+44 493 collected by the Cosmic Origins Spectrograph on the Hubble Space Telescope. We derive [P/Fe]=-0.34 +/- 0.21, [S/Fe]=+0.07 +/- 0.41, and [Zn/Fe]=-0.10 +/- 0.24. We increase by ten-fold the number of Si I lines detected in BD+44 493, yielding [Si/Fe]=+0.15 +/- 0.22. The solar [S/Fe] and [Zn/Fe] ratios exclude the hypothesis that the abundance pattern in BD+44 493 results from depletion of refractory elements onto dust grains. Comparison with zero-metallicity supernova models suggests that the stellar progenitor that enriched BD+44 493 was massive and ejected much less than 0.07 Msun of Ni-56, characteristic of a faint supernova.