@StartsWithABang Hi @StartsWithABang , the Type Ia supernova community has made a lot of recent progress on an explosion mechanism that doesn't involve the Chandrasekhar mass at all.

@StartsWithABang These "sub-Chandrasekhar-mass" explosions are triggered by a helium shell detonation that causes a subsequent core detonation.

@StartsWithABang Most relevant for the question at hand, this "double detonation" may be triggered in a double white dwarf system that is just beginning to merge, but before the companion white dwarf has been completely tidally pulled apart.

@StartsWithABang In this case, the companion will survive and will fly away from the system at thousands (!) of km/s because the gravitational pull of the exploding white dwarf has disappeared.

@StartsWithABang Three of these extreme hypervelocity stars have been discovered and are very, very strong evidence that this scenario actually happens in nature!

ui.adsabs.harvard.edu/abs/2018ApJ...865...15S/abstract