Abstract:
A new mechanism for Type Ia supernova explosions in massive white
dwarfs is discussed.  The scenario follows from relaxing assumptions
of symmetry and involves a detonation born near the stellar surface.
The explosion begins with an essentially central ignition of a
deflagration that results in the formation of a buoyancy-driven bubble
of hot material that reaches the stellar surface at supersonic speeds.
The bubble breakout laterally accelerates fuel-rich outer stellar
layers that carry enough mass and energy to trigger a detonation just
above the stellar surface. The stellar expansion following the
deflagration redistributes mass in a way that ensures production of
intermediate-mass and iron group elements with ejecta having a
strongly layered structure and a mild amount of asymmetry.  This
asymmetry, combined with the amount of stellar expansion determined by
details of the evolution, can be expected to create a family of mildly
diverse Type Ia supernova explosions.