Beryllium and boron in metal-poor stars

Abstract

Knowledge of lithium, beryllium, and boron abundances in stars of the Galactic halo and disk plays a major role in our understanding of Big Bang nucleosynthesis, cosmic-ray physics, and stellar interiors. 9 Be and 10 B are believed to originate entirely from spallation reactions in the interstellar medium (ISM) between α-particles and protons and heavy nuclei like carbon, nitrogen, and oxygen (CNO), whereas 11 B may have an extra production channel via neutrino-spallation. Beryllium and boron are both observationally challenging, with their main resonant doublets falling respectively at 313 nm and at 250 nm. The advent of 8-10m class telescopes equipped with highly sensitive (in the near-UV/blue) spectrographs has opened up a new era of Be abundance studies. Here, I will review and discuss the most interesting results of recent observational campaigns in terms of formation and evolution of these two light elements.