On the thermonuclear runaway in type ia supernovae: how to run away?

摘要: Type Ia supernovae (SNe Ia) are thought to be thermonuclear explosions of massive white dwarfs (WDs). We present the first study multidimensional effects during final hours prior runaway that leads explosion. The calculations utilize an implicit, two-dimensional hydrodynamic code. Mixing and ignition process studied in detail. find initial chemical structure WD is changed, but material not fully homogenized. In particular, exploding sustains a central region with low C/O ratio. This implies explosive nuclear burning will begin partially carbon-depleted environment. happens well-defined close center. It induced by compressional heat when matter brought inward convective flows. no evidence for multiple spot or strong off-center ignition. Convective velocities on order 100 km s-1, which well above effective speeds SNe previously expected right after runaway. our calculations, occurs near Then, ≈ 0.5-1 s, speed front neither determined laminar nor Rayleigh-Taylor instabilities flows produced consequences discussed understanding detailed physics flame propagation, deflagration detonation transition, nucleosynthesis layers. Our results strongly suggest preconditioning progenitor as key factor diversity Ia.