Abstract
Type Ia supernovae (SNe Ia) are believed to occur as a result of the thermonuclear explosion of a carbon-oxygen white dwarf. Despite intense research over the last several decades, the exact progenitor channel and detonation mechanism of SNe Ia remain unknown. In this thesis, I will present hydrodynamical simulations of helium-ignited double-degenerate white dwarf mergers, a promising scenario that could lead to successful SN Ia events as well as faint nova-like transients. I highlight the production of a key radioactive isotope, ⁴⁴Ti, and its potential use for discriminating between different SN Ia progenitor channels. Lastly, I will discuss the relevance of ⁴⁴Ti production via white dwarf merger events for the Galactic positron problem.