Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)




Dr. P. G. Sutherland


Despite great theoretical progress the nature of the progenitors of Type I supernovae is still in doubt. In recent years much attention has been focussed on accreting white dwarf models. This thesis examines another class of possible progenitors: extended helium stars. The computer code BOMB was written to hydrodynamically evolve the models.

A total of seventeen models are examined. Five of them resemble R Cor Bor stars which are hydrogen-deficient pulsational variables of roughly 1.5 - 2.0 M₀ named after the archetype R-Corona Borealis. Ten other models are variations on these, used to explore the parameter space of possible models. The remaining two models are of the bare white dwarf type which constitute the current orthodoxy in the field.

It is found that the R Cor Bor stars are not viable as Type I supernova progenitors. The bare white dwarf models fit the available data better than do any of the envelope models, although stars with relatively small, low-mass envelopes could also provide reasonable fits.

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