PHYS/ASTR Colloquium: "Delayed Explosions of Red Supergiants Following `Failed' Supernovae" - Andrea Antoni (PhD Candidate, UC Berkeley)

Red supergiants (RSGs) are the most common stars that will undergo iron core collapse. Successful explosions of RSGs following core-collapse lead to the most common supernovae, Type IIp. However, a fraction of core-collapse events may not lead to an immediate supernova explosion of the RSG. In those cases, a large fraction of the hydrogen envelope will fall in towards the newly-formed black hole. The angular momentum content of the infalling material determines whether accretion power can be liberated into driving an outflow or powering a luminous transient. I will show that, even in non-rotating RSGs, the random velocity field in the convective envelope carries significant angular momentum in each shell. Using 3D hydrodynamical simulations, I will also show that infall of the convective envelope generates an energetic outflow. This drives nearly complete envelope ejection in an explosion with an energy of at least 10^48 ergs and with outflow speeds of hundreds of km/s. The light curve of such an event would exhibit a characteristic, red plateau with a luminosity of at least ~few x 10^40 ergs and a duration of several hundreds of days. These events would appear quite similar to luminous red novae with red or yellow supergiant progenitors.