  The observation of neutrinos from Supernova 1987A has confirmed the
theoretical conjecture that these particles play a crucial role during the
collapse of the core of a massive star. Only one per cent of the energy they
carry away from the newly formed neutron star may account for all the kinetic
and electromagnetic energy responsible for the spectacular display of the
supernova explosion. However, the neutrinos emitted from the collapsed stellar
core at the center of the explosion couple so weakly to the surrounding matter
that convective processes behind the supernova shock and/or inside the nascent
neutron star might be required to increase the efficiency of the energy
transfer to the stellar mantle and envelope. The conditions for a successful
explosion by the neutrino-heating mechanism and the possible importance of
convection in and around the neutron star are shortly discussed.
Neutrino-driven explosions turn out to be very sensitive to the parameters
describing the neutrino emission of the proto-neutron star and to the details
of the dynamical processes in the collapsed stellar core. Therefore uniform
explosions with a well defined energy seem unlikely and type-II supernova
explosions do not offer promising perspectives for being useful as standard
candles.
