2000/01/26 by Franziska Brachwitz, David J. Dean, W. Raphael Hix +10 · 5 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Cosmic Phenomena #Chandrasekhar limit #Ejecta #Electron #Electron capture #Gamma-ray bursts and supernovae #Light curve #Stellar evolution #Supernova #White dwarf #astro-ph
paper · pdf · doi:10.1086/308968
26 pages, 8 figures, submitted to ApJ
arxiv created 2000/01/26 · openalex publication_date 2000/06/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
The Chandrasekhar-mass model for Type Ia supernovae (SNe Ia) has received increasing support from recent comparisons of observations with light-curve predictions and modeling of synthetic spectra. It explains SN Ia events via thermonuclear explosions of accreting white dwarfs in binary stellar systems, being caused by central carbon ignition when the white dwarf approaches the Chandrasekhar mass. As the electron gas in white dwarfs is degenerate, characterized by high Fermi energies for the high-density regions in the center, electron capture on intermediate-mass and Fe group nuclei plays an important role in explosive burning. Electron capture affects the central electron fraction Y e , which determines the composition of the ejecta from such explosions. Up to the present, astrophysical tabulations based on shell model matrix elements were available only for light nuclei in the sd -shell. Recently, new shell model Monte Carlo and large-scale shell model diagonalization calculations have also been performed for pf -shell nuclei. These lead in general to a reduction of electron capture rates in comparison with previous, more phenomenological, approaches. Making use of these new shell model-based rates, we present the first results for the composition of Fe group nuclei produced in the central regions of SNe Ia and possible changes in the constraints on model parameters like ignition densities ρ ign and burning front speeds v def .