In this review I will present and discuss both the nova outburst and the theoretical calculations related to its cause and evolution. I use the commonly accepted model for a nova: a close binary system with one member a white dwarf and the other member a larger, cooler star that fills its Roche lobe. Because it fills its lobe, any tendency for it to grow in size because of evolutionary processes or for the lobe to shrink because of angular momentum losses will cause a flow of gas through the inner Lagrangian point into the lobe of the white dwarf. The size of the white dwarf is small compared to the size of its lobe and the high angular momentum of the transferred material causes it to spiral into an accretion disk surrounding the white dwarf. Some viscous process, as yet unknown, acts to transfer mass inward and angular momentum outward through the disk so that a fraction of the material lost by the secondary ultimately ends up on the white dwarf. Over a long period of time, the accreted layer will grow in thickness until the bottom reaches a temperature that is high enough to initiate thermonuclear burning of hydrogen by the proton-proton reaction chain. The further evolution of thermonuclear burning on the white dwarf now depends upon the mass and luminosity of the white dwarf, the rate of mass accretion, and the chemical composition of the reacting layer.
Radio-to-gamma-ray Synchrotron and Neutrino Emission from Proton-proton Interactions in Active Galactic Nuclei
