SuperGiant -> SuperNova
There have been different “types” of supernovas observed. Type I and Type II. This discussion is about Type II supernovas. Type I will be discussed separately.
Type II supernovas are thought to originate from supergiant stars. There are O-type stars and also known as “blue supergiants”. The thing that really makes them “super” is their luminosity (energy output) which is on the order of 100,000 times that of the Sun. The table at this reference indicates that 99.9 % of all stars have luminosity less that 25 times that of the Sun. Some “bluish” stars can go up to 25,000 times the Sun’s luminosity, and these represent about 1 in a thousand stars.
However, the really powerful supergiants, 50,000 times the Sun’s luminosity represent only 60,000 stars out of the 200,000,000,000 stars in the Milky Way galaxy. These stars are thought to be Type II pre-supernova stars.
Several of these blue supergiants have been associated with pulsars and supernova explosions. The Crab was thought to be a blue supergiant. The SN1987A supernova is “known” to have been a blue supergiant, which had been observed before the supernova, but has disappeared since the supernova.
The remnants of the Crab emit 75,000 times the energy of the Sun, so despite the fact that the original blue supergiant that was the Crab before 1054 AD emitted on the order of 75,000 times the luminosity of the Sun (Ls), it is remarkable that after this supergiant exploded that it is still emitting 75,000 time Ls. Where does this huge luminosity (energy emission) come from? It appears to be powered by the 10 mile diameter neutron star pulsar at the center of the approximately 5 light-year diameter supernova remnant, the Crab Nebula.
Finally, the Cen X-3 pulsar’s companion is a blue supergiant as well. And it also emits on the order of 100,000 Ls.
The conclusion from this evidence that we can begin to believe is that it is not the supergiant stars themselves that are emitting this huge amount of energy, but that it is the neutron star associated with the giant star that is pumping the energy into the giant star that turns it into a supergiant, and the energy from the neutron star that is emitted in x-rays is absorbed by the atmosphere of the companion giant star, which is then re-emitted at lower frequencies which gives the blue supergiants their apparent luminosity.
i.e. blue supergiants in fact are regular B-type giants that captured a neutron star, which then turned them into blue supergiants, which, because of the huge energy they are absorbing from the presence of the neutron star will eventually destabilize the star by heating it to a level where the material of the star no longer will be bound by self-gravitation and will explode as a supernova.