The evolution of 6Li in standard cosmic-ray nucleosynthesis

Brian D. Fields, Keith A. Olive

Research output: Contribution to journalArticle

58 Scopus citations

Abstract

We review the Galactic chemical evolution of 6Li and compare these results with recent observational determinations of the lithium isotopic ratio. In particular, we concentrate on so-called standard Galactic cosmic-ray nucleosynthesis in which Li, Be, and B are produced (predominantly) by the inelastic scattering of accelerated protons and α off of CNO nuclei in the ambient interstellar medium. If O/Fe is constant at low metallicities, then the 6Li versus Fe/H evolution - as well as Be and B versus Fe/H - has difficulty in matching the observations. However, recent determinations of Population II oxygen abundances, as measured via OH lines, indicate that O/Fe increases at lower metallicity; if this trend is confirmed, then the 6Li evolution in a standard model of cosmic-ray nucleosynthesis is consistent with the data. We also show that another key indicator of 6LiBeB origin is the 6Li/Be ratio which also fits the available data if O/Fe is not constant at low metallicity. Finally we note that 6Li evolution in this scenario can strongly constrain the degree to which 6Li and 7Li are depleted in halo stars.

Original languageEnglish (US)
Pages (from-to)255-263
Number of pages9
JournalNew Astronomy
Volume4
Issue number4
DOIs
StatePublished - Jul 1999

Keywords

  • 26.35.+c
  • 26.40.+r
  • 98.70.Sa
  • 98.80.Ft
  • Cosmic rays
  • Galaxies: abundances
  • Nuclear reactions, nucleosynthesis, abundances

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