Astronomy and Astrophysics – Astrophysics
Scientific paper
1998-11-20
Astronomy and Astrophysics
Astrophysics
16 pages, 4 figures
Scientific paper
10.1016/S1384-1076(99)00015-9
The primordial abundances of Deuterium, he4, and li7 are crucial to determination of the baryon density of the Universe in the framework of standard Big Bang nucleosynthesis (BBN). li6 which is only produced in tiny quantities and it is generally not considered to be a cosmological probe. However, recent major observational advances have produced an estimate of the li6/li7 ratio in a few very old stars in the galactic halo which impacts the question whether or not the lithium isotopes are depleted in the outer layers of halo stars, through proton induced reactions at the base of (or below) the convective zone. li6 is a pure product of spallation through the major production reactions, fast oxygen and alphas interacting on interstellar H, He (especially in the early Galaxy). The rapid nuclei are both synthesized and accelerated by SN II. In this context, the \li6 evolution should go in step with that of beryllium and boron, recently observed by the Keck and HST telescopes. Li6 adds a new constraint on the early spallation in the Galaxy. In particular, if confirmed, the Li6/Be9 ratio observed in two halo stars (HD 84937, BD +263578) gives strong boundary conditions on the composition and the spectrum of the rapid particles involved. We show that Li6 is essentially intact in halo stars, and a fortiori \li7. We can define a range of the Li6 abundance in the very early Galaxy consistent with Big Bang nucleosynthesis (5.6 10(-14) to 3. 10(-13) . Following the evolution at increasing metallicity, we explain the abundance in the solar system within a factor of about 2.
Audouze Jean
Cass'e Michel
Cayrel Roger
Spite Francois
Spite Monique
No associations
LandOfFree
Lithium-6 : Evolution from Big Bang to Present does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Lithium-6 : Evolution from Big Bang to Present, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lithium-6 : Evolution from Big Bang to Present will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-634522