Progenitors of core-collapse supernovae
  Knowledge of the progenitors of core-collapse supernovae is a fundamental
component in understanding the explosions. The recent progress in finding such
stars is reviewed. The minimum initial mass that can produce a supernova has
converged to 8 +/- 1 solar masses, from direct detections of red supergiant
progenitors of II-P SNe and the most massive white dwarf progenitors, although
this value is model dependent. It appears that most type Ibc supernovae arise
from moderate mass interacting binaries. The highly energetic, broad-lined Ic
supernovae are likely produced by massive, Wolf-Rayet progenitors. There is
some evidence to suggest that the majority of massive stars above ~20 solar
masses may collapse quietly to black-holes and that the explosions remain
undetected. The recent discovery of a class of ultra-bright type II supernovae
and the direct detection of some progenitor stars bearing luminous blue
variable characteristics suggests some very massive stars do produce highly
energetic explosions. The physical mechanism is open to debate and these SNe
pose a challenge to stellar evolutionary theory.
