W. David Arnett, Regents Professor of Astrophysics at University of Arizona and developer of a new three-dimensional model for supernovae, provides explanation to observations not accounted for by previous models. His three dimensional model shows how the turbulent mixture of elements within the stellar structure causes it to expand, contract, and spew stellar material prior to its final detonation.
Previous models depicted a stellar cloud with heavier elements in the center, with gravitation attracting the surrounding material and heating up the whole as it contracts. Intense heat creates neutrinos that escape the star and take energy away from the system. Loss of energy results in further contraction of the star and faster heating/neutrino production. Limitations of models done in one or two dimensions prevent explanation of turbulent forces, and generally depict a smooth transition into the explosion.
The new model differs with the old in that it accounts for the turbulent forces that eject stellar remnants from the star as heavy elements violently stir with the lighter, as opposed to a steady contraction. His model is able to illustrate the phenomena observed in several supernovae where the stars do not simply diminish and explode. The stars that exhibit this turbulence are fighting back against the contraction, showing multiple peaks of precursor activity before the final detonation. He concludes that we may need to reconsider our understanding of what an explosion is before we may understand this stellar phenomena.
http://www.sciencedaily.com/releases/2014/03/140318113628.htm
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