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

TL;DR

This study uses 2D hydrodynamic simulations to explore how mixed hydrogen/helium flames behave in X-ray bursts, revealing that initial composition and reaction networks significantly influence flame propagation and ignition mechanisms.

Contribution

It provides new insights into the effects of initial composition and reaction networks on flame dynamics in X-ray bursts through detailed simulations.

Findings

Increased hydrogen reduces flame energy and speed.

Flame formation and runaway burning depend on initial conditions.

Secondary flame ignition occurs at late times, influenced by composition.

Abstract

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.