We are studying convection in mixed H/He X-ray bursts with the low Mach number hydrodynamics code Maestro. Our goal is to understand how a multi-dimensional treatment of the convection alters the nucleosynthesis.

We are modeling mixed H/He X-ray bursts with our low Mach number hydrodynamics code Maestro. The nucleosynthesis is described by a 10-nuclei network that approximates hot-CNO, 3-alpha, and rp-process breakout. These simulations are done in a plane-parallel geometry, with a 6 cm resolution. These calculations follow on from our initial pure He simulations. Our two-dimensional results are described in the following papers:

Multidimensional Modeling of Type I X-ray Bursts. I. Two-Dimensional Convection Prior to the Outburst of a Pure He Accretor [IOP]
Malone, C. M., Nonaka, A. J., Almgren, A. S., Bell, J. B., & Zingale, M., 2011, ApJ, 728, 118
Multidimensional Modeling of Type I X-ray Bursts. II. Two-Dimensional Convection in a Mixed H/He Accretor [arvix]
Malone, C. M., Zingale, M., Nonaka, A., Almgren, A. S., & Bell, J. B., 2014, ApJ, 788, 115
Comparisons of Two- and Three-Dimensional Convection in Type I X-ray Bursts
Zingale, M., Malone, C. M., Nonaka, A., Almgren, A. S., & Bell, J. B., 2015, ApJ, 807, 60

A model of a mixed H/He burst is shown below:

Most recently, we've begun working on three-dimensional simulations:

Acknowledgements: The work at Stony Brook was supported by a DOE/Office of Nuclear Physics grant No. DE-FG02-06ER41448 and DE-FG02-87ER40317 to Stony Brook. The work at LBNL was supported by the Applied Mathematics Program of the DOE Office of Advance Scientific Computing Research under U.S. Department of Energy under contract No. DE-AC02-05CH11231. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. An award of computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. This research used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725.