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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1965

Nucleosynthesis.

Nucleosynthesis in stars including light element reactions, helium and carbon burning, neutrino processes, etc

NUCLEOSYNTHESIS↗
NASA NTRS1967

Supernova hydrodynamics and nucleosynthesis.

Core of two solar masses of gravitationally collapsing star, analyzing hydrodynamics, heating, helium 4 formation, neutron decay, nucleosynthesis, light output and mass ejection

SUPERNOVA↗
NASA NTRS1971

Nucleosynthesis in the Magellanic Clouds and the Galaxy.

Available evidence on the chemical composition of the Magellanic Clouds (when compared to the Galaxy) is not sufficient for a detailed theory of the chemical evolution of the Clouds to be developed at present. However, this evidence is thus far compatible with the view that much of the material of the Clouds went through a considerable amount of nucleosynthesis early in its history. The Clouds could once have been part of the Galaxy, or they could have formed as satellites when the protogalaxy condensed. The general problem of the chemical evolution is tied closely to the problem of galaxy formation which remains unsolved.

Burbidge, G.↗
NASA NTRS1971

Evolutionary models of nucleosynthesis in the galaxy.

A model of the galaxy is constructed and evolved in which the integrated influence of stellar and supernova nucleosynthesis on the composition of the interstellar gas is traced numerically. Our detailed assumptions concerning the character of the matter released from evolving stars and supernovae are guided by the results of recent stellar evolutionary calculations and hydrodynamic studies of supernova events. It is difficult to visualize an epoch of massive star formation in the collapsing gas cloud which formed our galaxy which would enrich the gas rapidly enough to account for the level of heavy element abundances in halo population stars; we have therefore proposed a stage of star formation which is entirely pregalactic in character. We suggest that the Jeans' length-sized initial condensations in the expanding universe discussed by Peebles and Dicke may provide the appropriate setting for this first generation of stars. Guided by these considerations, and by the need for a substantial quantity of 'unseen' mass to bind our local group of galaxies, we have constructed a model of the galaxy in which this violent early phase of massive star formation produces both (1) approximately 25% of the level of heavy elements observed in the solar system and (2) an enormous unseen mass in the form of black holes.

Truran, J. W.↗
NASA NTRS1973

Consistency of cosmic-ray source abudances with explosive nucleosynthesis

A model was examined in which the cosmic ray abundances of elements from C to Fe are consistent with explosive nucleosynthesis. The observed abundance of cosmic rays near the earth, cosmic ray source abundance, and solar system abundance are discussed along with the ratios of cosmic ray sources to the solar system abundances.

Kozlovsky, B.↗
NASA NTRS1975

Carbon-burning nucleosynthesis with convection

The effect of convection on carbon-burning nucleosynthesis is explored with a limited network of reactions. Convection is simulated by a series of networks at fixed mass points in the core of an evolving 15 solar mass star. Complete mixing is always assumed. Comparison to single network calculations show that the 'half-energy' approximation of Arnett yields reasonable results, although the abundances of nuclei which are created by beta-decays of unstable nuclei tend to be underestimated, by this approximation.

Endal, A. S.↗
NASA NTRS1975

Nucleosynthesis of He-3 in the sun and the variation of He-3/He-4 in solar wind

The time history of the variation of He-3/He-4 (R) on the surface of the sun as a result of nucleosynthesis in the solar interior has been studied for different empherical models of mixing. For homogeneous mixing with mixing periods between one million and 1,000 millions years, the expected value of R is very much larger than the observed solar wind value. On the other hand, the absolute value of R and its possible time variation in the solar wind are consistent with a model in which slow mixing with adjacent layers, equivalent to about 0.01 Mr, of the core takes place over a period of 100 million years. The possibility of explaining the He-3 rich solar flare events is discussed.

Stephens, S. A.↗