We show that the observed Li versus Fe trend provides a strong discriminant between alternative models for Galactic chemical evolution of the light elements at early epochs.
We show that the observed Li versus Fe trend provides a strong discriminant between alternative models for Galactic chemical evolution of the light elements at early epochs.We critically assess current systematic uncertainties and determine the primordial Li abundance within new, much tighter limits: (Li/H) is now limited as much by uncertainties in the nuclear cross sections used in big bang nucleosynthesis (BBN) calculations as by the observed abundance itself.Lighter elements, such as hydrogen and helium, were created in the Big Bang when the universe began.Tags: University Of Washington Essay PromptEssay On Why Violent Video S Should Not Be BannedHigh School Science Essay CompetitionThesis AcknowledgeScholarship Essay StructureEasy Topics For Comparison EssayWrite An Outline For An EssayEssayons Unit Crest
He, which they mix into the convective envelope on the giant branch and should distribute into the Galaxy by way of envelope loss.
This process is so efficient that it is difficult to reconcile the low observed cosmic abundance of He with the predictions of both stellar and Big Bang nucleosynthesis.
Recent determinations of the abundance of the light-element Li in very metal-poor stars show that its intrinsic dispersion is essentially zero and that the random error in the estimated mean Li abundance is negligible.
However, a decreasing trend in the Li abundance toward lower metallicity indicates that the primordial abundance of Li can be inferred only after allowing for nucleosynthesis processes that must have been in operation in the early history of the Galaxy.
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