When the supernova impostor SN2009ip brightened to a V-band absolute magnitude of -17.7 near the end of 2012, the outburst was classified as a Type IIn supernova and many observers thought the star had finally exploded for good. In this paper, however, the authors present several months of multiband imaging of transient 2012b and argue that the low limit on the nickel mass and lack of most heavy elements in the ejecta suggest the progenitor is still around, and that transient 2012b was produced instead by the collision of two massive shells, possibly ejected by the pulsational pair instability.
Pakmor et al. propose a new mechanism to make Type 1a supernova explosions from a pair of white dwarfs.
Super-luminous supernovae are a recently discovered rare class of stellar explosions with luminosities 10 – 100 times higher than normal supernovae. We summarize what is known about how these events are powered.