2000/06/07 by E. Parizot, Etienne Parizot, Parizot, Etienne
Physics and Astronomy · #Astro and Planetary Science #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0006099
14 pages, 6 figures, A&A in press
arxiv created 2000/06/07 · openalex publication_date 2000/06/07 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
From a recent re-analysis of the available data, Be and B Galactic evolution appears to show evidence for a two-slope behaviour with respect to O. The inferred Be/O abundance ratio in halo stars is constant at very low metallicity (primary behaviour) and increases proportionally to O/H at high metallicity (secondary behaviour). We show that this can be explained in the framework of one single model, the `superbubble model', in which Li, Be and B are produced by spallation reactions induced by energetic particles accelerated out of a mixture of supernova (SN) ejecta and ambient interstellar medium inside superbubbles (SBs). All the qualitative and quantitative constraints, including the energetics, the value of the transition metallicity and the 6Li/9Be isotopic ratio, are satisfied provided that the energetic particles have a spectrum flattened at low energy (in E-1) and that the proportion of the SN ejecta inside SBs is of the order of a few percent. This lends support to Bykov's acceleration mechanism inside SBs and to the SB dynamical evolution model of Mac Low & McCray (1988).