ABSTRACT
In the previous chapter we discussed the evolution of stars from their initial condensation out of the large gas and dust clouds to their final stages as white or red dwarfs on the slow decline to eventual extinction, and saw how the various evolutionary phases are intimately associated with the nuclear processes taking place in their interiors. Certain of these reactions lead to unstable conditions inside the star, resulting in short-term changes in the energy output which in turn give rise to various classes of variable star. The instabilities which have been considered so far, however, are comparatively mild and on a relatively small scale. Those with which we shall now be dealing are of a much more violent nature, sometimes resulting in the almost complete disruption of the star itself.
