Supernova in lost common envelope and SN 2006gy

Abstract

A mechanism is proposed for synchronizing core-collapse supernova with a recent loss of a red supergiant (RSG) envelope in the common envelope regime. A perequisite for the synchronization is a moderate RSG expansion during final decade. This scenario is based on the phenomenon of preSN~II dense shell formed at the final stage of 10-20 yr as a result of powerfull mass loss. The energy deposition into the RSG envelope that powers the enormous mass loss rate is able to expand the RSG. The moderate expansion is sufficient for the close secondary component to plunge into the common envelope with a subsequent explosion of stripped helium core. Superluminous SN~2006gy is suggested to be the outcome of this scenario.