@phdthesis{BolanosRosales2016,
  author    = {Bola{\~n}os-Rosales, Alejandro},
  title     = {Low Mach Number Simulations of Convective Boundary Mixing in Classical Novae},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-132863},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2016},
  abstract  = {Classical novae are thermonuclear explosions occurring on the surface of white dwarfs. When co-existing in a binary system with a main sequence or more evolved star, mass accretion from the companion star to the white dwarf can take place if the companion overflows its Roche lobe. The envelope of hydrogen-rich matter which builds on top of the white dwarf eventually ignites under degenerate conditions, leading to a thermonuclear runaway and an explosion in the order of 1046 erg, while leaving the white dwarf intact. Spectral analyses from the debris indicate an abundance of isotopes that are tracers of nuclear burning via the hot CNO cycle, which in turn reveal some sort of mixing between the envelope and the white dwarf underneath. The exact mechanism is still a matter of debate. The convection and deflagration in novae develop in the low Mach number regime. We used the Seven League Hydro code (SLH ), which employs numerical schemes designed to correctly simulate low Mach number flows, to perform two and three- dimensional simulations of classical novae. Based on a spherically-symmetric model created with aid of a stellar evolution code, we developed our own nova model and tested it on a variety of numerical grids and boundary conditions for validation. We focused on the evolution of temperature, density and nuclear energy generation rate at the layers between white dwarf and envelope, where most of the energy is generated, to understand the structure of the transition region, and its effect on the nuclear burning. We analyzed the resulting dredge-up efficiency stemming from the convective motions in the envelope. Our models yield similar results to the literature, but seem to depend very strongly on the numerical resolution. We followed the evolution of the nuclear species involved in the CNO cycle and concluded that the thermonuclear reactions primarily taking place are those of the cold and not the hot CNO cycle. The reason behind this could be that under the conditions generally assumed for multi-dimensional simulations, the envelope is in fact not degenerate. We performed initial tests for 3D simulations and realized that alternative boundary conditions are needed.},
  subject      = {Nova},
  language  = {en}
}
@phdthesis{Pfannes2006,
  author    = {Pfannes, Jan M. M.},
  title     = {Explosions of Rotating White Dwarfs},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-20872},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2006},
  abstract  = {The impact of rapid rotation of the supernova progenitor star (white dwarf) on its explosion (type Ia supernova) is investigated. Different explosion mechanisms are employed.},
  subject      = {Weißer Zwerg},
  language  = {en}
}