Nucleosynthesis hydrogen burning

Big Bang nucleosynthesis (cosmic nucleosynthesis) Proton-proton cycle Triple He collisions Alpha capture CNO cycle Neutron capture High-energy photon collisions produce antimatter-matter pairs. This leads to H,D, He and some Li nuclei Hydrogen burning to produce He 12C production Addition of 4He to the nucleus Production of 13C, 13N, 14N and 150 Post-Fe nuclei... 

LO) that surrounds the degenerate C-0 core. Although the hydrogen-burning shell is not an active site of neutron capture nucleosynthesis, it is where raw materials for this nucleosynthesis, such as 4He and 14N, are created. This 4He will be fuel for the following thermal pulse and the 4He and 14N may be reactants in the neutron capture nucleosynthesis reactions. 

The first stage of stellar nucleosynthesis, which is still occurring in stars such as our sun, is hydrogen burning. In hydrogen burning, protons are converted to 4He nuclei. Since there are no free neutrons present, the reactions differ from those of Big Bang nucleosynthesis. The first reaction that occurs is... 

We begin with a discussion of the poorly understood mechanisms for heavy-element nucleosynthesis and some of our efforts to understand these environments. Then we turn to a discussion of the exotic environments for hot hydrogen burning and some of our experimental and theoretical efforts to obtain the associated nuclear data. 

In the mix of interstellar atoms from which the solar system formed, 17O exists primarily owing to the hydrogen-burning process of stellar nucleosynthesis. 170 is made by converting a fraction of the 16 O to 170 by the nuclear reaction... 

There are several lines of evidence that nucleosynthesis takes place in stars. The compositions of the outer envelopes of evolved low- and intermediate-mass stars show enhancements of the products of nuclear reactions (hydrogen and helium burning and s-process nucleosynthesis, as defined below). The ejecta of supemovae (stellar explosions) are highly enriched in short-lived radioactive nuclides that can only have been produced either just before or during the explosion. At the other extreme, low-mass stars in globular clusters, which apparently formed shortly after the universe formed, are deficient in metals (elements heavier than hydrogen and helium) because they formed before heavy elements were synthesized. 

In this review we wish to discuss how observations of AGB stars can be used to determine the manner in which heavy elements are created during a thermal pulse, and how these heavy elements and carbon are transported to the stellar surface. In particular we wish to study how the periodic hydrogen and helium shell burning above a degenerate carbon-oxygen (C-0) core forms a neutron capture nucleosynthesis site that may eventually account for the observed abundance enhancements at the surfaces of AGB stars. In section II we discuss the nucleosynthesis provided by stellar evolution models (for a general review see [1]). In section III we discuss the isotopic abundances provided by nucleosynthesis reaction network calculations (see [2, 3]). In section IV we discuss how observations of AGB stars can be used to discriminate between the neutron capture nucleosynthesis sources (see [4]). And in section V we note some of the current uncertainty in this work. 

Our beloved sun that warms up the Earth from above burns hydrogen in a cycle of fusion reactions that was discovered by Hans Bethe, a German scientist who received the Nobel Prize in physics in 1967 for his understanding of nucleosynthesis in the sun. 

It is on the TP-AGB that the richest nucleosynthesis occurs for low and intermediate-mass stars, even though stars spend such a short amount of time there compared to previous evolutionary phases. The nucleosynthesis is driven by thermal instabilities of the helium-burning shell, reviewed in Sect. 4. Of particular importance is the action of repeated third dredge-up events that mix the products of He-burning to the stellar surface. Material from the He-shell will become part of the next hydrogen shell, where they will experience proton captures during the next interpulse period. For this reason, not only do we need to consider nucleosynthesis in the thermal pulse itself but also... 

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