Exploring the Diversity in Hydrogen-Deficient Supernovae

Our physical understanding of the processes underlying supernovae (SNe) is still incomplete. This can in parts be improved by detailed observations. In this thesis, hydrogen-deficient core-collapse SNe (type Ib/c) and thermonuclear SNe (type Ia) are considered, the focus being on peculiar objects and - closely related - the diversity encountered in these explosions. In particular, an underluminous type Ia SN, whose spectra suggest a large amount of unburned material and a low metallicity of the precursor star, and a relatively energetic type Ic SN, which might provide a link between "normal" type Ic SNe and those highly energetic "hypernovae" related to gamma-ray bursts, are studied. In addition, emission-line profiles are analysed in a large number of type Ib/c nebular spectra, allowing conclusions on the geometry of the ejected matter to be drawn.