SIRIUS: Identifying Metal-poor Stars Enriched by a Single Supernova in a Dwarf Galaxy Cosmological Zoom-in Simulation Resolving Individual Massive Stars

TL;DR

This study uses a detailed cosmological simulation to identify and analyze metal-poor stars enriched by a single supernova in a dwarf galaxy, revealing their distribution and prevalence at different metallicities.

Contribution

It introduces a novel simulation-based method to identify mono-enriched stars and quantifies their fraction among metal-poor stars at various metallicities.

Findings

Mono-enriched stars are more common at lower metallicities.

11% of stars at [Fe/H] = -5.0 are mono-enriched.

Only 1% of stars at [Fe/H] = -2.5 are mono-enriched.

Abstract

Metal-poor stars enriched by a single supernova (mono-enriched stars) are direct proof (and provide valuable probes) of supernova nucleosynthesis. Photometric and spectroscopic observations have shown that metal-poor stars have a wide variety of chemical compositions; the star's chemical composition reflects the nucleosynthesis process(es) that occurred before the star's formation. While the identification of mono-enriched stars enables us to study the ejecta properties of a single supernova, the fraction of mono-enriched stars among metal-poor stars remains unknown. Here we identify mono-enriched stars in a dwarf galaxy cosmological zoom-in simulation resolving individual massive stars. We find that the fraction of mono-enriched stars is higher for lower metallicity, stars with [Fe/H] $< -2.5$. The percentages of mono-enriched stars are 11% at [Fe/H] = $-$5.0 and 1% at [Fe/H] = $-$2.5, suggesting that most metal-poor stars are affected by multiple supernovae. We also find that mono-enriched stars tend to be located near the center of the simulated dwarf. Such regions will be explored in detail in upcoming surveys such as the Prime Focus Spectrograph (PFS) on the Subaru telescope.