SN 1987 A: an astrophysicist's point of view

SN 1987 A has been a peculiar object, mostly by its optical emission rather than by its neutrino signature. Indeed, the Kamioka and IMB detections were in good agreement with the energy release expected from the formation of a neutron star by the core collapse mechanism while the supernova optical rise time, visible and UV color evolution, light curve and progenitor star were unusual. It was rapidly realized that most of these peculiarities could be explained by the fact that the progenitor was a blue supergiant of radius R* = 40 - 50 solar radius, instead of a red supergiant with R* ∼ 1000 solar radius. By fitting the light curve, important constraints were obtained on explosion parameters, such as the shock energy or the mass of synthetized 56Ni. However, the conditions for which a massive star can explode in the blue supergiant phase are still not well understood due to uncertainties in the models, especially in the treatment of convection and in the mass loss rates