Effects of nuclear uncertainties and chemical evolution on the standard big bang nucleosynthesis

Abstract

It is shown that consistent predictions of baryonic densities can be made only for some specific galactic-evolution models involving D and He-3: either the infall of already processed material such that D/Dp = 1/15 (where Dp is the primordial abundance of D and D is the present value) or the effect of stellar mass loss releasing D free He-3 rich material (amounting to 20 percent of the total mass of the star) during the pre-main sequence phase of the stellar evolution. This latter hypothesis can explain the observations of Rood et al. (1984) of large He-3 abundances at large galactocentric distances. Consideration is also given to other sources of uncertainties concerning the relation between predictions of standard big-bang nucleosynthesis and observations of rates of nuclear reactions producing and destroying Li-7.