Nuclear composition and heating in accreting neutron-star crusts

Abstract

Nuclear reactions in accreting neutron-star crusts and the heat release accompanying them are studied, under different assumptions concerning the composition of the outermost layer formed of the ashes of X-ray bursts. Particular examples of ashes containing nuclides with are considered and compared with a standard case. In all cases, evolution of a crust shell is followed from to a few times . The total crustal heating produced in the non-equilibrium processes in the accreting crust is per one accreted nucleon. The composition of the accreted crust at densities exceeding the threshold for the pycnonuclear fusion () is essentially independent of the assumed initial composition of the X-ray burst ashes.