SIMBAD references

The evolutionary path of rotating CO white dwarfs (WD) directly accreting CO-rich matter is followed up to a few seconds before the explosive breakout in the framework of the double degenerate (DD) rotationally driven accretion scenario. We compute several models with different initial masses and physical conditions, following all the evolutionary phases, from the heating process during the pre-merging phase, through the two self-regulated accretion phases, up to the final central C-ignition and the development of an extended convective core.

We find that the evolutionary properties (both structural and observational) depend only on the actual mass of the accreting WD and not on the previous history. We determine the expected frequency and amplitude of the gravitational wave emission, which occurs during the mass transfer process and, as a matter of fact, acts as a self-tuning mechanism of the accretion process itself. The gravitational signal related to Galactic sources can be easily detected with the next generation of space-born interferometers and can provide notable constraints to the progenitor model. The expected statistical distribution of pre-explosive objects in the Galaxy is provided also in the effective temperature-apparent bolometric magnitude diagrams which can be used to identify merged DD systems via UV surveys, once the contribution of the accretion disc is properly taken into account.

We emphasize that the thermonuclear explosion occurs owing to the decay of physical conditions keeping overstable the structure above the classical Chandrasekhar limit and not by a steady increase of the WD mass up to this limit. This conclusion is independent of the evolutionary scenario for the progenitors, but it is a direct consequence of the stabilizing effect of rotation. Such an occurrence represents an epistemological change of the perspective in defining the ignition process for accreting WDs. Moreover, this requires a long evolutionary period (of at least several million years) to attain the explosion after the above mentioned conditions cease to keep stable the WD. Therefore, it is practically impossible to detect the trace of the exploding WD companion in recent pre-explosion frames of even very near Type Ia supernova events.