and oxygen are left, being mixed down to the central region.

In contrast, the detonation wave produces a more layered structure, since this supersonically propagating wave is unaffected by hydrodynamic instabilities (at least on the large scales resolved in the models). In the C-DDT model, the deflagration burns out much of the center of the WD before the detonation is triggered. Therefore, the detonation mainly burns material towards the stellar surface, but it also propagates down the fuel funnels between the fingers of the deflagration ash (Fig. 1). In the C-DDT model, the whole WD, including the central region, experiences the strong expansion in the vigorous deflagration stage. Therefore, the unburned material left after the deflagration is processed in the detonation stage mainly by carbon and oxygen burning, producing O and IME, but virtually no Fe-peak elements (Fig. 2). In this particular model, Fe-peak elements are thus produced mostly in the initial deflagration stage.

In the O-DDT model the burning proceeds in an aspherical manner. Figures 4 and 5 show the temporal evolution in the O-DDT model. The deflagration frame, ignited off-center, floats outward, and spreads laterally (Röpke et al. 2007d). It creates a large blob of ashes in the 