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Title: THE DETONATION MECHANISM OF THE PULSATIONALLY ASSISTED GRAVITATIONALLY CONFINED DETONATION MODEL OF Type Ia SUPERNOVAE

Abstract

We describe the detonation mechanism composing the 'pulsationally assisted' gravitationally confined detonation (GCD) model of Type Ia supernovae. This model is analogous to the previous GCD model reported in Jordan et al.; however, the chosen initial conditions produce a substantively different detonation mechanism, resulting from a larger energy release during the deflagration phase. The resulting final kinetic energy and {sup 56}Ni yields conform better to observational values than is the case for the 'classical' GCD models. In the present class of models, the ignition of a deflagration phase leads to a rising, burning plume of ash. The ash breaks out of the surface of the white dwarf, flows laterally around the star, and converges on the collision region at the antipodal point from where it broke out. The amount of energy released during the deflagration phase is enough to cause the star to rapidly expand, so that when the ash reaches the antipodal point, the surface density is too low to initiate a detonation. Instead, as the ash flows into the collision region (while mixing with surface fuel), the star reaches its maximally expanded state and then contracts. The stellar contraction acts to increase the density of the star, includingmore » the density in the collision region. This both raises the temperature and density of the fuel-ash mixture in the collision region and ultimately leads to thermodynamic conditions that are necessary for the Zel'dovich gradient mechanism to produce a detonation. We demonstrate feasibility of this scenario with three three-dimensional (3D), full star simulations of this model using the FLASH code. We characterized the simulations by the energy released during the deflagration phase, which ranged from 38% to 78% of the white dwarf's binding energy. We show that the necessary conditions for detonation are achieved in all three of the models.« less

Authors:
; ; ; ; ;  [1];  [2];  [3];  [4];  [5]
  1. Flash Center for Computational Science, University of Chicago, Chicago, IL 60637 (United States)
  2. Department of Physics, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02740 (United States)
  3. Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487 (United States)
  4. Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
  5. NTEC Environmental Technology, Subiaco WA 6008 (Australia)
Publication Date:
OSTI Identifier:
22086467
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 759; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASHES; ASTRONOMY; ASTROPHYSICS; BINDING ENERGY; COLLISIONS; COMPUTERIZED SIMULATION; DENSITY; ELEMENT ABUNDANCE; HYDRODYNAMICS; KINETIC ENERGY; NICKEL 56; NUCLEAR REACTION YIELD; NUCLEOSYNTHESIS; SUPERNOVAE; SURFACES; WHITE DWARF STARS

Citation Formats

Jordan, G. C. IV, Graziani, C., Weide, K., Norris, J., Hudson, R., Lamb, D. Q., Fisher, R. T., Townsley, D. M., Meakin, C., and Reid, L. B. THE DETONATION MECHANISM OF THE PULSATIONALLY ASSISTED GRAVITATIONALLY CONFINED DETONATION MODEL OF Type Ia SUPERNOVAE. United States: N. p., 2012. Web. doi:10.1088/0004-637X/759/1/53.
Jordan, G. C. IV, Graziani, C., Weide, K., Norris, J., Hudson, R., Lamb, D. Q., Fisher, R. T., Townsley, D. M., Meakin, C., & Reid, L. B. THE DETONATION MECHANISM OF THE PULSATIONALLY ASSISTED GRAVITATIONALLY CONFINED DETONATION MODEL OF Type Ia SUPERNOVAE. United States. doi:10.1088/0004-637X/759/1/53.
Jordan, G. C. IV, Graziani, C., Weide, K., Norris, J., Hudson, R., Lamb, D. Q., Fisher, R. T., Townsley, D. M., Meakin, C., and Reid, L. B. Thu . "THE DETONATION MECHANISM OF THE PULSATIONALLY ASSISTED GRAVITATIONALLY CONFINED DETONATION MODEL OF Type Ia SUPERNOVAE". United States. doi:10.1088/0004-637X/759/1/53.
@article{osti_22086467,
title = {THE DETONATION MECHANISM OF THE PULSATIONALLY ASSISTED GRAVITATIONALLY CONFINED DETONATION MODEL OF Type Ia SUPERNOVAE},
author = {Jordan, G. C. IV and Graziani, C. and Weide, K. and Norris, J. and Hudson, R. and Lamb, D. Q. and Fisher, R. T. and Townsley, D. M. and Meakin, C. and Reid, L. B.},
abstractNote = {We describe the detonation mechanism composing the 'pulsationally assisted' gravitationally confined detonation (GCD) model of Type Ia supernovae. This model is analogous to the previous GCD model reported in Jordan et al.; however, the chosen initial conditions produce a substantively different detonation mechanism, resulting from a larger energy release during the deflagration phase. The resulting final kinetic energy and {sup 56}Ni yields conform better to observational values than is the case for the 'classical' GCD models. In the present class of models, the ignition of a deflagration phase leads to a rising, burning plume of ash. The ash breaks out of the surface of the white dwarf, flows laterally around the star, and converges on the collision region at the antipodal point from where it broke out. The amount of energy released during the deflagration phase is enough to cause the star to rapidly expand, so that when the ash reaches the antipodal point, the surface density is too low to initiate a detonation. Instead, as the ash flows into the collision region (while mixing with surface fuel), the star reaches its maximally expanded state and then contracts. The stellar contraction acts to increase the density of the star, including the density in the collision region. This both raises the temperature and density of the fuel-ash mixture in the collision region and ultimately leads to thermodynamic conditions that are necessary for the Zel'dovich gradient mechanism to produce a detonation. We demonstrate feasibility of this scenario with three three-dimensional (3D), full star simulations of this model using the FLASH code. We characterized the simulations by the energy released during the deflagration phase, which ranged from 38% to 78% of the white dwarf's binding energy. We show that the necessary conditions for detonation are achieved in all three of the models.},
doi = {10.1088/0004-637X/759/1/53},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 759,
place = {United States},
year = {2012},
month = {11}
}