Type Ia supernovae (SNeIa) are bright astrophysical explosions that form a remarkably homogeneous class of objects used to study the expansion history of the Universe and the nature of Dark Energy. However, details of the explosion mechanism and the influence of properties of the host stellar population remain incompletely understood. The most widely accepted scenario for a SNIa to occur is the explosion of a near-Chandrasekhar mass white dwarf. Under this scenario, the thermonuclear explosion begins as a deflagration (subsonic burning) near the center that transitions to a detonation (supersonic burning) some time later. Turbulence, particularly its interaction with the flame, plays a key role throughout the evolution of the explosion process. Pre-existing turbulence from a vigorous convection field encompassing roughly 70% of the star will influence the evolution of the early flame, while turbulence generated by fluid instabilities is thought to interact with the flame such that a deflagration-to-detonation transition (DDT) occurs. As I will show, the DDT density strongly influences the yield of radioactive 56Ni that powers the light curve. While the conditions under which a DDT occurs remains an area of active research, it is thought to be influenced by the metallicity of the progenitor. I will offer an explanation of observed trends in the peak brightness of SNeIa with host galaxy metallicity from results of a suite of two-dimensional simulations in which the DDT density was varied. I will also present improvements to our flame model for the enhancement of burning by turbulence and discuss its application in three-dimensional simulations of the impact of pre-existing turbulence on the early flame evolution. This work was supported by NASA under grant No. NNX09AD19G.
American Astronomical Society Meeting Abstracts #217
- Pub Date:
- January 2011