[en] The structure of strong shock waves is calculated over the range of shock energies (1 to 100 MeV/nucleon) and initial number densities (10¹⁵--10²² cm^-3) believed likely to occur in the red-giant-like envelopes of stars undergoing type II supernovae explosions. The general equations governing the structure of such shocks are developed on the basis of a hydrodynamic treatment of a plasma composed of ions, electrons, positrons, and photons, making use of diffusion theory to evaluate the dissipative and transfer terms. Several strong shock structure models are formulated and solved on the basis of these equations and physical processes. A shock model dominated by radiation pressure and transport is considered and criteria for its self consistency deduced. For electron temperatures above approximately 70 keV, the γγ reversible e⁺e^- reaction is found to give rise to a sufficient number of pairs to cause the principal source of shock dissipation to shift from radiative heat transport to ion-lepton Coulomb friction. The properties of such a pair-dominated model are discussed. The stability of radiation-dominated shocks and the lack of self-consistent hot-ion shocks is demonstrated. This demonstration leads to the conclusion that peak shock temperatures remain low enough to preclude production of a cosmologically significant amount of deuterium in supernova shock waves. The application of these concepts is considered. (U.S.)

[en] The possibility of producing high-energy neutrinos (> approx. 10 GeV) in relativistic supernova shock waves is considered. It is shown that, even if the dissipation in such shocks is due to hard hadron--hadron collisions, the resulting flux of neutrinos is too small to be observed by currently envisioned detectors. The associated burst of hard γ-rays, however, may be detectable. 3 tables

[en] Under the National Resource Evaluation (NURE), massive amounts of geological, geochemical, and geophysical data, covering the entire conterminous 48 states and Alaska, are being collected and made public. In addition to NURE goals, these data are applicable to various other researches on and in the vicinity of lands controlled by the National Park Service. Airborne geophysical and hydrogeochemical survey NURE data have been made public for the majority of the area in the combined Mt. McKinley National Park and Denali National Monument. Besides indicating potential raw material deposits, these data are also useful for geologic mapping, water quality, pollution and othe geological, biological, and environmental studies in the park

[en] Recent measurements of nonsolar isotopic patterns for the elements neon and (perhaps) magnesium in cosmic rays are interpreted within current models of stellar nucleosynthesis. One possible explanation is that the stars currently responsible for cosmic-ray synthesis in the Galaxy are typically super-metal-rich by a factor of two to three. Other possibilities include the selective acceleration of certain zones or masses of supernovas or the enhancement of ²²Ne in the interstellar medium by mass loss from red giant stars and planetary nebulas. Measurements of critical isotopic ratios are suggested to aid in distinguishing among the various possibilities. Some of these explanations place significant constraints on the fraction of cosmic ray nuclei that must be fresh supernova debris and the masses of the supernovas involved. 1 figure, 3 tables

[en] Three alternatives to fusion power are described with reference to their particular promise. A brief outline of the research needed to accurately assess their potential utility is given. The three alternatives are: (1) moderate rhor standard fuel reactors, (2) advanced fuel systems (pB¹¹, pLi⁶, pBe⁹), and (3) neutronic Compton generators

[en] An attempt is reported to build self-consistent evolutionary models of complete massive stars, starting from their observable zero-age main sequence configurations, and evolving through their various hydrostatic nuclear burning stages, iron core collapse, bounce, outward-going shock formation, and finally, explosive nucleosynthesis and supernovae light curve formation. The model incorporates implicit hydrodynamics with a new treatment of time-dependent convection and semiconvection, and a careful treatment of the complexities of the advanced stages of stellar burning. The model was used to completely evolve population I stars of 15 and 25 M/sub solar mass/, with excellent agreement with the known properties and the prediction of other properties. 65 references

[en] Net energy generation rates and f-factors are calculated for a variety of two component DT reactor configurations using a computer code that follows the energy distributions of the reactants and products explicitly, utilizing the Fokker--Planck approximation for low-angle Coulomb scattering and a transfer matrix for high-angle Coulomb, nuclear, and radiative processes. The relative importance of such non-thermal effects as alpha particle deposition, non-Maxwellian energy distributions for the target tritons and electrons, and the influence of high-angle Coulomb and nuclear scattering on the energy loss rate of the injected deuterons is explicitly assessed

[en] Presupernova models of massive stars are presented and their explosion by ''delayed neutrino transport'' examined. A new form of long duration Type II supernova model is also explored based upon repeated encounter with the electron-positron pair instability in stars heavier than about 60 Msub solar. Carbon deflagration in white dwarfs is discussed as the probable explanation of Type I supernovae and special attention is paid to the physical processes whereby a nuclear flame propagates through degenerate carbon. 89 refs., 12 figs

[en] The current status of our understanding of Type II supernovae is reviewed with particular emphasis on the processes responsible for the emission of electromagnetic radiation. In addition, a relatively novel evolutionary scenario that appears to lead to a Type I supernova explosion is presented

[en] The results of recent numerical simulations of supernova explosions are presented and a variety of topics discussed. Particular emphasis is given to (i) the nucleosynthesis expected from intermediate mass (10sub solar less than or equal to M less than or equal to 100 Msub solar) Type II supernovae and detonating white dwarf models for Type I supernovae, (ii) a realistic estimate of the γ-line fluxes expected from this nucleosynthesis, (iii) the continued evolution, in one and two dimensions, of intermediate mass stars wherein iron core collapse does not lead to a strong, mass-ejecting shock wave, and (iv) the evolution and explosion of vary massive stars M greater than or equal to 100 Msub solar of both Population I and III. In one dimension, nuclear burning following a failed core bounce does not appear likely to lead to a supernova explosion although, in two dimensions, a combination of rotation and nuclear burning may do so. Near solar proportions of elements from neon to calcium and very brilliant optical displays may be created by hypernovae, the explosions of stars in the mass range 100 M/sub solar/ to 300 M/sub solar/. Above approx. 300 M/sub solar/ a black hole is created by stellar collapse following carbon ignition. Still more massive stars may be copious producers of ⁴He and ¹⁴N prior to their collapse on the pair instability