New Primary Mechanisms for the Synthesis of Rare 9Be in Early Supernovae

TL;DR

This paper introduces two new primary mechanisms for synthesizing the rare isotope 9Be in early supernovae, involving neutrino-induced reactions in the helium shells of progenitors with different masses.

Contribution

It identifies novel nucleosynthesis pathways for 9Be in supernovae, triggered by neutrino interactions, expanding understanding of light element formation in astrophysical environments.

Findings

New mechanisms for 9Be production in supernovae identified.

Distinct patterns in LiBeB production could differentiate these mechanisms.

Mechanisms depend on progenitor mass and explosion conditions.

Abstract

We present two new primary mechanisms for the synthesis of the rare nucleus 9Be, both triggered by nu-induced production of 3H followed by 4He(3H,gamma)7Li in the He shells of core-collapse supernovae. For progenitors of ~8M_sun, 7Li(3H,n_0)9Be occurs during the rapid expansion of the shocked He shell. Alternatively, for ultra-metal-poor progenitors of ~11-15M_sun, 7Li(n,gamma)8Li(n,gamma)9Li(e^-anti-nu_e)9Be occurs with neutrons produced by 4He(anti-nu_e,e^+n)3H, assuming a hard effective anti-nu_e spectrum from oscillations (which also leads to heavy element production through rapid neutron capture) and a weak explosion (so the 9Be survives shock passage). We discuss the associated production of 7Li and 11B, noting patterns in LiBeB production that might distinguish the new mechanisms from others.