The beryllium abundance in the very metal-poor halo star G 64-12 from VLT/UVES observations

TL;DR

This study presents the first precise measurement of beryllium in the extremely metal-poor star G 64-12, revealing unexpectedly high Be levels that challenge existing models of early galactic chemical evolution.

Contribution

It provides the first Be abundance measurement in a star with [Fe/H] = -3.3 using high-resolution UVES spectra, highlighting potential deviations in Be evolution at low metallicity.

Findings

Be abundance is higher than expected for its metallicity.

The [Be/Fe] ratio suggests possible flattening or dispersion in early Be evolution.

High-resolution spectroscopy enabled accurate Be measurement at very low metallicity.

Abstract

We report on a new spectroscopic analysis of the very metal deficient star G 64-12 ([Fe/H]=-3.3), aimed at determining, for the first time, its Be content. The spectra were observed during the Science Verification of UVES, the ESO VLT Ultraviolet and Visible Echelle Spectrograph. The high resolution (~48,000) and high S/N (~130 per pixel) achieved at the wavelengths of the BeII resonance doublet allowed an accurate determination of its abundance: log N(Be/H) = -13.10 +/- 0.15 dex. The Be abundance is significantly higher than expected from previous measurements of Be in stars of similar metallicity (3D and NLTE corrections acting to make a slightly higher value than an LTE analysis). When compared to iron, the high [Be/Fe] ratio thus found may suggest a flattening in the beryllium evolutionary trend at the lowest metallicity end or the presence of dispersion at early epochs of galactic evolution.