Tables of Nuclear Cross Sections and Reaction Rates: an Addendum to the Paper "Astrophysical Reaction Rates from Statistical Model Calculations"

In a previous publication [Atomic Data and Nuclear Data Tables 75, 1 (2000)], we had given seven parameter analytical fits to theoretical reaction rates derived from nuclear cross sections calculated in the statistical model (Hauser-Feshbach formalism) for targets with 9<Z<84 (Ne to Bi) and for a mass range reaching the neutron and proton driplines. Reactions considered were (n,gamma), (n,p), (n,alpha), (p,gamma), (p,alpha), (alpha,gamma), and their inverse reactions. On public demand, we present here the theoretical nuclear cross sections and astrophysical reaction rates from which those rate fits were derived, and we provide these data as on-line electronic files. Corresponding to the fitted rates, two complete data sets are provided, one of which includes a phenomenological treatment of shell quenching for neutron-rich nuclei.Comment: 23 pages, 3 tables; scheduled to appear in Atomic Data Nuclear Data Tables 79 (2001) (September issue); preprint and data also available at http://quasar.physik.unibas.ch/~tommy/adndt.htm

Global statistical model calculations and the role of isospin

An improved code for the calculation of astrophysical reaction rates in the statistical model is presented. It includes the possibility to study isospin effects. Such effects heavily affect capture rates involving self-conjugate nuclei and may also be found in reactions on other intermediate and heavy targets.Comment: 5 pages LaTeX, uses iopconf.sty, to appear in the proceedings of the 2nd Oak Ridge Symposium on Atomic and Nuclear Astrophysics, ed. A. Mezzacappa, IOP, in pres

Nucleosynthesis in Type Ia Supernovae

Among the major uncertainties involved in the Chandrasekhar mass models for Type Ia supernovae are the companion star of the accreting white dwarf (or the accretion rate that determines the carbon ignition density) and the flame speed after ignition. We present nucleosynthesis results from relatively slow deflagration (1.5 - 3 % of the sound speed) to constrain the rate of accretion from the companion star. Because of electron capture, a significant amount of neutron-rich species such as ^{54}Cr, ^{50}Ti, ^{58}Fe, ^{62}Ni, etc. are synthesized in the central region. To avoid the too large ratios of ^{54}Cr/^{56}Fe and ^{50}Ti/^{56}Fe, the central density of the white dwarf at thermonuclear runaway must be as low as \ltsim 2 \e9 \gmc. Such a low central density can be realized by the accretion as fast as \dot M \gtsim 1 \times 10^{-7} M_\odot yr^{-1}. These rapidly accreting white dwarfs might correspond to the super-soft X-ray sources.Comment: 10 page LaTeX, 7 PostScript figures, to appear in Nuclear Physics A, Vol. A621 (1997

Nucleosynthesis in Type II Supernovae

Presupernova evolution and explosive nucleosynthesis in massive stars for main-sequence masses from 13 $M_\odot$ to 70 $M_\odot$ are calculated. We examine the dependence of the supernova yields on the stellar mass, ^{12}C(\alpha, \gamma) ^{16}O} rate, and explosion energy. The supernova yields integrated over the initial mass function are compared with the solar abundances.Comment: 1 Page Latex source, 10 PostScript figures, to appear in Nuclear Physics A, Vol. A616 (1997

Long-term evolution of massive star explosions

We examine simulations of core-collapse supernovae in spherical symmetry. Our model is based on general relativistic radiation hydrodynamics with three-flavor Boltzmann neutrino transport. We discuss the different supernova phases, including the long-term evolution up to 20 seconds after the onset of explosion during which the neutrino fluxes and mean energies decrease continuously. In addition, the spectra of all flavors become increasingly similar, indicating the change from charged- to neutral-current dominance. Furthermore, it has been shown recently by several groups independently, based on sophisticated supernova models, that collective neutrino flavor oscillations are suppressed during the early mass-accretion dominated post-bounce evolution. Here we focus on the possibility of collective flavor flips between electron and non-electron flavors during the later, on the order of seconds, evolution after the onset of an explosion with possible application for the nucleosynthesis of heavy elements.Comment: 12 pages, 7 figures, conference proceeding, HANSE 2011 worksho