By all rights, stars should be stable, sober creatures, preferring to die with a whimper than with a bang. Astronomers have struggled to understand why some of them go supernova. These explosions have resisted efforts to describe them in a simplified way, making them perhaps the most complex phenomena in all of astrophysics.
Theorists have gradually ratcheted up the sophistication of their models and have recently succeeded at last in reproducing the two main types of supernovae. The key has been to capture all three spatial dimensions in fine enough detail to track the turbulent flow dynamics.
They have discovered that the explosions can be seriously lopsided, stirring the debris (which includes newly synthesized chemical elements) thoroughly. In the kind of explosion that leaves behind a neutron star, this star recoils and careens across the galaxy at high speed.
Wolfgang Hillebrandt, Hans-Thomas Janka and Ewald Müller