[aerohead]

I went back through the workbook which accompanied the DVD astronomy course.
At end of life,massive stars become gravitationally unstable,experience a core collapse,blow away their outer plasma layers in an enormous release of energy.
Core remnants will be either a neutron star or black hole.
All pulsars are formed this way.
These events are irreversible.
Repeating 'nova' from the same source are impossible.