Blue supergiant progenitor models of type II supernovae

We show that within all the uncertainties that govern the process of Roche-lobe overflow in case Br-type massive binaries, it cannot be excluded that a significant fraction of them merge and become single stars. We demonstrate that at least some of them will spend most of their core helium-burning phase as hydrogen-rich blue stars, populating the massive blue supergiant region and/or the massive Be-type star population. The evolutionary simulations lead us to suspect that these mergers will explode as luminous blue hydrogen-rich stars, and it is tempting to link them to at least some superluminous supernovae.