Multi-dimensional Models of Mixed H/He Flames in X-ray Bursts

We investigate the properties of mixed H/He flames in X-ray bursts using 2D hydrodynamic simulations. We find that as the initial hydrogen abundance of the atmosphere increases, the flame is less energetic and propagates slower. The simulation outcome, whether a flame forms and whether there’s runaway burning at the base of the atmosphere, is very sensitive to the initial model and the nuclear reaction network used. We also see that at late times a secondary flame ignites, with the ignition mechanism dependent on the composition.