Blue supergiants as a progenitor of intermediate-luminosity red transients.

This article investigates the diverse explosion outcomes of massive blue supergiants (BSGs), particularly focusing on how varying amounts of radioactive nickel-56 (⁵⁶Ni) influence their supernova light curves. While the well-known SN 1987A-like events—characterized by slow-rising, dome-shaped light curves—result from BSG explosions with relatively high ⁵⁶Ni masses (≳0.01 solar masses), the study finds that BSG explosions with lower ⁵⁶Ni masses produce low-luminosity, short-plateau Type II supernovae resembling some intermediate-luminosity red transients (ILRTs) and Type II SNe like SN 2008bp. Using binary-merger progenitor models evolved to core carbon depletion and radiation hydrodynamics simulations, the authors demonstrate that BSG explosions are more varied than previously thought and that some ILRTs may originate from faint BSG explosions with small ⁵⁶Ni yields. This work helps reconcile the discrepancy between the expected frequency of BSGs from binary mergers and the rarity of SN 1987A-like supernovae observed.