Reconciling Big Bang and Stellar Nucleosynthesis  

By Peter P. Eggleton , David S.P Dearborn, john C. Lattanizo

reported by Pengcheng liu
 
Based on the theory of Big Bang and stellar nucleosynthesis, we could obsevre  a large
amount of Helium-3 which is the byproduct of the proton-proton chain reaction. however the low observed helium-3 become a threat of these two theory. The author of the article model a red giant with fully 3D hydrodynamic code and a full nucleosythesis network, the mixing happened in the region between the hydrogen-burning shell and the base of the convective envelope is more fast than what the original theory estimated. after fixing the problem, there are still have some further issue reqirue investigation, which involve rotation and magnetic field of the model.
 
Background information   

The theory that the universe began in a state of extremely high density and has been expanding since some particular instant that marked the origin of the universe. The big bang is the generally accepted cosmological theory; the incorporation of developments in elementary particle theory has led to the inflationary universe version. The predictions of the inflationary universe and older big bang theories are the same after the first 10?35 s. See also Inflationary universe cosmology.

Two observations are at the base of observational big bang cosmology. First, the universe is expanding uniformly, with objects at greater distances receding at a greater velocity. Second, the Earth is bathed in the cosmic background radiation, an isotropic glow of radiation that has the characteristics expected from the remnant of a hot primeval fireball.

Stellar nucleosynthesis is the collective term for the nuclear reactions taking place in stars to build the nuclei of the heavier elements. (For other such processes, see nucleosynthesis.)

PP chain

The proton-proton chain reaction is one of two fusion reactions by which stars convert hydrogen to helium, the other being the CNO cycle. The proton-proton chain dominates in stars the size of the Sun or less.

To overcome the electromagnetic repulsion between two hydrogen nuclei requires a large amount of energy, and this reaction takes an average of 109 years to complete at the temperature of the Sun's core. Because of the slowness of this reaction the Sun is still shining; if it were faster, the Sun would have exhausted its hydrogen long ago.

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