Reaction Rates for Dense Matter Burning

Karl-Ludwig Kratz Universität Mainz Email: [email protected] An interesting question in nuclear astrophysics is the fate of post X-ray burst matter. Once an accreting neutron star has undergone thermonuclear runaway, the ashes of the burst are forced down into the crust of the neutron star. With increasing density a volume element of matter undergoes a number of electron captures and neutron emissions, resulting in low mass neutron rich nuclei. At sufficiently high densities pycnonuclear reactions can set in. We recently formulated [1] a single phenomenological expression for the calculation of pycnonuclear reaction rates which is not only valid in mixed component plasma, but can also be extended to cover the five stellar burning regimes. Here we use this expression in concert with a dynamic reaction network code to model the neutron star crust composition at high densities.