UC Santa Barbara

Accretion of helium onto white dwarfs at various rates can lead to several different types of explosive outcomes.

Slow accretion from low mass He stars or He WDs in binaries with orbital periods less than an hour can build up helium shells of ${\approx}0.1 M_\odot$ that ignite and detonate, generating faint and fast transients.

In this dissertation, I explore this well known channel for generating transients from He accretion onto WDs, as well as with less explored channels that accrete He onto WD at rates that allow for steady helium shell burning.

Stable helium burning significantly grows the degenerate core, which can result in several different outcomes, including type Ia supernovae and accretion induced collapse.

I also explore deep convection in C/O/Ne hybrid WDs and found effective mixing to a level that will strongly affect their later explosions.

Some binaries are unstable to mass transfer and merge the component stars.

Previous studies explored explosive outcomes during the merger, whereas I studied a channel that leads to a unique type of explosion ${\approx}10^5$ years after the merger event.

Additionally, I made some predictions about observed compact binaries with He stars and He WDs.