1998/06/05 by Elisabeth Vangioni-Flam, E. Vangioni–Flam, Reuven Ramaty +7
Physics and Astronomy · #Astro and Planetary Science #Astrophysics (astro-ph) #FOS: Physical sciences #Gamma-ray bursts and supernovae #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9806084
14 pages, latex, 4 ps figures
arxiv created 1998/06/05 · openalex publication_date 1998/06/05 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Two types of models have been proposed to explain the linear rise of the Be and B abundances as a function of iron observed in metal poor halo stars. In both cases, this linearity indicates that freshly synthesized C and O are accelerated by Type II supernovae and subsequently fragmented into Be and B. One mechanism advocates shock acceleration in the gaseous phase of superbubbles excavated by collective SNII explosions. Because of their short lifetimes, only the most massive stars (with an initial mass greater than 60\msun) do not drift out of superbubbles, and participate in BeB production. The second mechanism is based on the acceleration of the debris of grains formed in the ejecta of all SNIIs (originating from stars with initial mass greater than 8\msun). Here again, fresh C and O are sped up to cosmic ray energies by shocks. We propose a possible test to discriminate between the two scenarios. If supernovae of all masses are involved in BeB production, the Be/Fe ratio is constant, since both elements are produced in the same events. Alternatively, when only the most massive stars are involved in Be production, Be/Fe is enhanced at very early times because of the shorter lifetimes of these stars. This predicted difference in the behavior of Be/Fe could be tested by high quality observations at [Fe/H] \lsim -3. We also note that the solution invoking only the most massive supernovae mimics a flat evolution of both Be/H and B/H as a function of Fe/H at low metallicity, and could thus resemble a "plateau" for these elements despite a lack of a primordial Big Bang nucleosynthesis origin. Consequently, there may be no need to invoke inhomogeneous Big Bang models to explain the initial production of BeB should a plateau be discovered.