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Title: On silicon group elements ejected by supernovae type IA

There is evidence that the peak brightness of a Type Ia supernova is affected by the electron fraction Y {sub e} at the time of the explosion. The electron fraction is set by the aboriginal composition of the white dwarf and the reactions that occur during the pre-explosive convective burning. To date, determining the makeup of the white dwarf progenitor has relied on indirect proxies, such as the average metallicity of the host stellar population. In this paper, we present analytical calculations supporting the idea that the electron fraction of the progenitor systematically influences the nucleosynthesis of silicon group ejecta in Type Ia supernovae. In particular, we suggest the abundances generated in quasi-nuclear statistical equilibrium are preserved during the subsequent freeze-out. This allows potential recovery of Y {sub e} at explosion from the abundances recovered from an observed spectra. We show that measurement of {sup 28}Si, {sup 32}S, {sup 40}Ca, and {sup 54}Fe abundances can be used to construct Y {sub e} in the silicon-rich regions of the supernovae. If these four abundances are determined exactly, they are sufficient to recover Y {sub e} to 6%. This is because these isotopes dominate the composition of silicon-rich material and iron-rich materialmore » in quasi-nuclear statistical equilibrium. Analytical analysis shows the {sup 28}Si abundance is insensitive to Y {sub e}, the {sup 32}S abundance has a nearly linear trend with Y {sub e}, and the {sup 40}Ca abundance has a nearly quadratic trend with Y {sub e}. We verify these trends with post-processing of one-dimensional models and show that these trends are reflected in the model's synthetic spectra.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8]
  1. School of Earth and Space Exploration, Arizona State University, Tempe, AZ (United States)
  2. Joint Institute for Nuclear Astrophysics, University of Notre Dame, IN 46556 (United States)
  3. Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY (United States)
  4. Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, AL (United States)
  5. Swiss National Supercomputing Centre, Via Trevano 131, 6900 Lugano (Switzerland)
  6. Physics Division, Argonne National Laboratory, Argonne, IL (United States)
  7. Laboratoire d'Astrophysique de Marseille, Marseille cedex 13 F-13388 (France)
  8. Departamento de Astronomía, Universidad de Guanajuato, Apartado Postal 144, 36000 Guanajuato (Mexico)
Publication Date:
OSTI Identifier:
22356765
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 787; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; BRIGHTNESS; CALCIUM 40; EQUILIBRIUM; EXPLOSIVES; IRON 54; METALLICITY; NUCLEAR REACTIONS; NUCLEOSYNTHESIS; ONE-DIMENSIONAL CALCULATIONS; SILICON; SILICON 28; SPECTRA; SULFUR 32; SUPERNOVAE; WHITE DWARF STARS