Ignition of Carbon Burning from Nuclear Fission in Compact Stars

Type Ia supernovae (SN Ia) are powerful stellar explosions that provide important distance indicators in cosmology. Recently, we proposed a new SN Ia mechanism that involves a nuclear fission chain reaction in an isolated white dwarf (WD). The first solids that form as a WD starts to freeze are actinide rich and potentially support a fission chain reaction. In this Letter, we explore thermonuclear ignition from fission heating. We perform thermal diffusion simulations and find at high densities, above about 7 × 10⁸ g cm⁻³, that fission heating can ignite carbon burning. This could produce an SN Ia or another kind of astrophysical transient.