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Models for Type I supernovae

Description: Two rather disjoint scenarios for Type I supernovae are presented. One is based upon mass accretion by a white dwarf in a binary system. The second involves a star having some 8 to 10 times the mass of the sun which may or may not be a solitary star. Despite the apparent dissimilarities in the models it may be that each occurs to some extent in nature for they both share the possibility of producing substantial quantities of /sup 56/Ni and explosions in stars devoid of hydrogen envelopes. These… more
Date: June 17, 1980
Creator: Woosley, S. E.; Weaver, T. A. & Taam, R. E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Optical pulsations in AM Her systems. Revision 1

Description: The AM Her systems are widely believed to be mass transfer binaries containing a white dwarf primary accreting from a red dwarf secondary. The magnetic field of the white dwarf is so strong that it prevents the formation of an accretion disk and funnels the accretion flow into the polar caps of the white dwarf. The accreting matter is decelerated from free fall by passage through a standoff shock located somewhat above the surface of the white dwarf. The hot postshock gas radiates hard x-rays a… more
Date: June 1, 1985
Creator: Langer, S.H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Neutrino emission by the pair, plasma, and photo processes in the Weinberg-Salam model

Description: The results of numerical integrations of the rates and emissivities of the photo, pair, and plasma neutrino emission mechanisms in the Weinberg-Salam theory of the weak interaction are presented. The range of densities 10 gm cm/sup -3/ less than or equal to rho < 10/sup 14/ gm cm/sup -3/ and the temperature range 10/sup 8/K less than or equal to T less than or equal to 10/sup 11/K are considered. Fitting formulae, similar to those provided by Beaudet, Petrosian, and Salpeter, which reproduce th… more
Date: June 1, 1986
Creator: Schinder, P. J.; Schramm, D. N.; Witta, P. J.; Margolis, S. H. & Tubbs, D. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Detailed photonuclear cross-section calculations and astrophysical applications

Description: We have investigated the role of an isomeric state and its coupling to the ground state (g.s.) via photons and neutron inelastic scattering in a stellar environment by making detailed photonuclear and neutron cross-section calculations for /sup 176/Lu and /sup 210/Bi. In the case of /sup 176/Lu, the g.s. would function as an excellent galactic slow- (s-) process chronometer were it not for the 3.7-h isomer at 123 keV. Our calculations predicted much larger photon cross sections for production o… more
Date: June 15, 1989
Creator: Gardner, D. G.; Gardner, M. A. & Hoff, R. W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Nonradial pulsations of hot evolved stars

Description: There are three classes of faint blue variable stars: the ZZ Ceti variables (DAV degenerate dwarfs), the DBV variables (DB degenerate dwarfs), and the GW Vir variables (DOV degenerate dwarfs). None of these classes of variable stars were known at the time of the last blue star meeting. Observational and theoretical studies of the ZZ Ceti variables, the DBV variables, and the GW Vir variables have shown them to be pulsating in nonradial g-modes. The cause of the pulsation has been determined for… more
Date: June 1987
Creator: Starrfield, Sumner G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Neutron capture cross sections for /sup 86/Sr and /sup 87/Sr at stellar temperatures. Revision 1

Description: Recent work on s-process nucleosynthesis has focused attention on the investigation of capture cross sections for nuclei in the mass region near the N = 50 closed neutron shell. Of special astrophysical interest are (i) the analysis of the s-process branching through /sup 85/Kr as a monitor of stellar neutron density and temperature and (ii) the investigation of the possible chronometric pair /sup 87/Rb-/sup 87/Sr as an independent measure of the age of the galaxy. For both problems the capture… more
Date: June 25, 1986
Creator: Bauer, R. W.; Mathews, G. J.; Becker, J. A.; Howe, R. E. & Ward, R. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Three-dimensional dynamics of protostellar evolution. [Nonlinear problems, kinetics]

Description: A three-dimensional finite difference numerical methodology was developed for self-gravitating, rotating gaseous systems. The fully nonlinear equations for time-varying fluid dynamics are solved by high speed computer in a cylindrical coordinate system rotating with an instantaneous angular velocity, selected such that the net angular momentum relative to the rotating frame is zero. The time-dependent adiabatic collapse of gravitationally bound, rotating, protostellar clouds is studied for spec… more
Date: June 1, 1977
Creator: Cook, T. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The evolution of baryon number density fluctuations before, during and after primordial nucleosynthesis

Description: The simultaneous evolution of weak and nuclear reactions along with baryon diffusion in isothermal fluctuations produced in the quark-hadron phase transition is discussed. We find that the resulting light-element nucleosynthesis is sensitive to the separation distance between fluctuations, although still consistent with observed light-element abundances (except possibly /sup 7/Li) for a reasonable range of separations between fluctuations. The heavy-element nucleosynthesis has been computed for… more
Date: June 1, 1988
Creator: Mathews, G. J.; Fuller, G. M.; Alcock, C. R. & Kajino, T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Pulsations and outbursts of luminous blue variables

Description: We propose an outburst mechanism for the most luminous stars in our and other galaxies. These million solar luminosity stars, with masses (after earlier mass loss) of between 20 and maybe 70 solar masses, are pulsationally unstable for both radial and low-degree nonradial modes. Some of these modes are ``strange,`` meaning mostly that the pulsations are concentrated near the stellar surface and have very rapid growth rates in linear theory. The pulsation driving is by both the high iron line op… more
Date: June 1, 1997
Creator: Cox, Arthur N.; Guzik, Joyce A.; Soukup, Michael S. & Despain, Kate M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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