Stationary Accretion Flow with Nuclear Burning

Abstract

We present a series of numerical solutions of spherically symmetric stationary flows with nuclear burning accreted by a neutron star (or black hole). We consider the accretion of matter composed of carbon and oxygen, which mimics the flow after a neutron star is engulfed by a CO star or the CO core of a massive star. It is found that there are two types of transonic solutions depending on the accretion rate. The flow with a low accretion rate reaches the center (or the surface of the central object) at supersonic speeds. The other type with a high accretion rate has another sonic point inside the transonic point and the flow truncates at the sonic point. The critical accretion rate dividing these two types is derived as a function of the mass of the central object and the specific enthalpy in the ambient matter. We discuss implications from the solutions for a new mechanism of super-Chandrasekhar Type Ia supernovae and Type Icn supernovae.