Electron-capture Supernovae of Super-AGB Stars: Sensitivity on Input Physics
Shing-Chi Leung, Ken’ichi Nomoto, Tomoharu Suzuki
Abstract
Abstract Stars of M ∼ 8–10 M ⊙ on their main sequence form strongly electron-degenerate oxygen–neon–magnesium (ONeMg) cores and become super–asymptotic giant branch stars. If such an ONeMg core grows to 1.38 M ⊙ , electron captures on 20 Ne( e , ν e ) 20 F( e , ν e ) 20 O take place and ignite O–Ne deflagration around the center. In this work, we perform two-dimensional hydrodynamical simulations of the propagation of the O–Ne flame to see whether such a flame triggers a thermonuclear explosion or induces a collapse of the ONeMg core due to subsequent electron capture behind the flame. We present a series of models to explore how the outcome depends on model parameters for a central density ranging between 10 9.80 and 10 10.20 g cm −3 , flame structures of both centered and off-centered ignition kernels, special and general relativistic effects, turbulent flame speed formulae, and the treatments of laminar burning phase. We obtain bifurcation between the electron-capture induced collapse and thermonuclear explosion depending mainly on the central density. We find that the ONeMg core obtained from stellar evolutionary models has a high tendency to collapse into a neutron star. We discuss the implications of the electron-capture supernovae in chemical evolution and the possible observational signals of this class of supernovae.