An unexplored enrichment stochasticity and its implications for stellar abundance patterns

TL;DR

This paper demonstrates that the chemical abundance patterns in extremely low metallicity stars can be better explained by inhomogeneous enrichment from normal supernovae rather than hypernovae, challenging previous assumptions.

Contribution

It introduces a model accounting for supernova ejecta inhomogeneity to explain peculiar stellar abundance patterns, prompting a reassessment of metal-poor star enrichment.

Findings

Abundance patterns are better explained by normal supernovae with inhomogeneous ejecta.

Reassessment of metal-poor stars' enrichment sources is necessary.

Highlights the importance of supernova ejecta inhomogeneity in stellar chemical analysis.

Abstract

Extremely low metallicity stars are intensely studied as they take observations the closest to the very first generations of stars in the universe. Widely assumed to be enriched by just one dying massive star, some of these very metal poor stars have abnormal chemical abundance ratios and have been taken to reflect a rare hypernova (with high explosion energy $\gtrsim \ 10^{52}$ erg.). Here we remodel the enrichment of three such stars and show that their abundances are better explained by enrichment from a normal (less energetic) supernova accounting for inhomogeneous distribution of the ejecta. This work establishes the importance of the inhomogeneity of supernovae, serves as a template for a required reassessment of all metal-poor/peculiar stars, and raises the need to quantify this inhomogeneity both in theory and in observations.