Possible signature of hypernova nucleosynthesis in a beryllium rich halo dwarf

TL;DR

This paper reports the discovery of a halo star with an unusually high beryllium abundance, suggesting it was formed near a hypernova, challenging standard galactic chemical evolution models.

Contribution

It presents the first known case of a star with hypernova signature in its chemical composition, highlighting a possible new nucleosynthesis process.

Findings

Star HD 106038 has beryllium abundance over ten times higher than similar stars.

The star shows overabundances of Li, Si, Ni, Y, and Ba, but not all can be explained by standard models.

Hypernova proximity is proposed as the origin of these chemical peculiarities.

Abstract

As part of a large survey of halo and thick disc stars, we found one halo star, HD 106038, exceptionally overabundant in beryllium. In spite of its low metallicity, [Fe/H] = -1.26, the star has log(Be/H) = -10.60, which is similar to the solar meteoritic abundance, log(Be/H) = -10.58. This abundance is more than ten times higher the abundance of stars with similar metallicity and cannot be explained by models of chemical evolution of the Galaxy that include the standard theory of cosmic-ray spallation. No other halo star exhibiting such a beryllium overabundance is known. In addition, overabundances of Li, Si, Ni, Y, and Ba are also observed. We suggest that all these chemical peculiarities, but the Ba abundance, can be simultaneously explained if the star was formed in the vicinity of a hypernova.