Neutrino Heating in an Inhomogeneous Big Bang Nucleosynthesis Model

The effect of the heating of neutrinos by scattering with electrons and positrons and by e-e+ annihilation on nucleosynthesis is calculated for a spherically symmetric baryon inhomogeneous model of the universe. The model has a high baryon density core and a low density outer region. The heating effect is calculated by solving the Boltzmann Transport Equation for the distribution functions of electron and muon/tau neutrinos. For a range of baryon-to-photon ratio = [ 0, 1.5 ] x 10^-10 and distance scale = [ 10^2, 10^8 ] cm the heating effect increases the mass fraction of He4 by a range of [1, 2] x 10^-4. The change of the value of the mass fraction of He4 appears similiar to the change caused by an upward shift in the value of the baryon-to-photon ratio. But the change to deuterium is a decrease in abundance ratio Y(d)/Y(p) on the order of 10^-3, one order less than the decrease due to a shift in baryon-to-photon ratio.Comment: 6 Pages, LaTeX, 6 Postscript Figures, to appear in "The 20th Texas Symposium on Relativistic Astrophysics", (Austin, TX, December 11-15, 2000), ed. J. Craig Wheeler and Hugo Marte

Neutron Diffusion and Nucleosynthesis in an Inhomogeneous Big Bang Model

This article presents an original code for Big Bang Nucleosynthesis in a baryon inhomogeneous model of the universe. In this code neutron diffusion between high and low baryon density regions is calculated simultaneously with the nuclear reactions and weak decays that compose the nucleosynthesis process. The size of the model determines the time when neutron diffusion becomes significant. This article describes in detail how the time of neutron diffusion relative to the time of nucleosynthesis affects the final abundances of He4, deuterium and Li7. These results will be compared with the most recent observational constraints of He4, deuterium and Li7. This inhomogeneous model has He4 and deuterium constraints in concordance for baryon to photon ratio eta = (4.3 - 12.3) X 10^{-10} Li7 constraints are brought into concordance with the other isotope constraints by including a depletion factor as high as 5.9. These ranges for the baryon to photon ratio and for the depletion factor are larger than the ranges from a Standard Big Bang Nucleosynthesis model.Comment: 7/15, added reference

Physical processes leading to surface inhomogeneities: the case of rotation

In this lecture I discuss the bulk surface heterogeneity of rotating stars, namely gravity darkening. I especially detail the derivation of the omega-model of Espinosa Lara & Rieutord (2011), which gives the gravity darkening in early-type stars. I also discuss the problem of deriving gravity darkening in stars owning a convective envelope and in those that are members of a binary system.Comment: 23 pages, 11 figure, Lecture given to the school on the cartography of the Sun and the stars (May 2014 in Besan\c{c}on), to appear in LNP, Neiner and Rozelot edts V2: typos correcte

Por que consumir pescado é estratégico para o Brasil?

bitstream/item/79994/1/ADM135.pdfFormato eletrônico. Disponível também em: Dourados News, Agronline, ZooNews, AgoraMS, BBC News, Folha do MS, Infobibos