# Evidence for an aspherical Population III supernova explosion inferred from the hyper metal-poor star HE1327-2326

## TL;DR

This study provides observational evidence suggesting that the first supernovae in the universe were likely aspherical hypernovae, influencing early chemical enrichment, based on detailed abundance analysis of a hyper metal-poor star.

## Contribution

First detection of zinc in a hyper metal-poor star and modeling indicating an aspherical hypernova explosion explains its abundance pattern.

## Key findings

- Detection of [Zn/Fe] = 0.80±0.25 in HE1327-2326
- Best match with a 25M$_{ ext{sun}}$ aspherical hypernova model
- Implication of bipolar outflows in early universe enrichment

## Abstract

We present observational evidence that an aspherical supernova explosion could have occurred in the First stars in the early universe. Our results are based on the First determination of a Zn abundance in a Hubble Space Telescope/Cosmic Origins Spectrograph high-resolution UV spectrum of a hyper metal-poor (HMP) star, HE1327-2326, with [Fe/H](NLTE) = -5.2. We determine [Zn/Fe] = 0.80$\pm$0.25 from a UV Zn I line at 2138 detected at $3.4\sigma$. Yields of a 25M$_{\odot}$ aspherical supernova model with artificially modified densities exploding with E = 5x10$^{51}$ ergs best match the entire abundance pattern of HE1327-2326. Such high-entropy hypernova explosions are expected to produce bipolar outfows which could facilitate the external enrichment of small neighboring galaxies. This has already been predicted by theoretical studies of the earliest star forming minihalos. Such a scenario would have significant implications for the chemical enrichment across the early universe as HMP Carbon Enhanced Metal-Poor (CEMP) stars such as HE1327-2326 might have formed in such externally enriched environments.