The prompt mechanism of Type II supernovae

An extensive set of hydrodynamical simulations of the stellar collapse of the cores of massive stars is reported. A new hydro technique and a series of state-of-the-art equations of state were employed. The purpose of this project was to understand in detail core implosion and immediate postbounce behavior (first 25 ms) and to investigate the viability of the hydrodynamic mechanism for Type II supernovae. It is found that the bounce-shock always stalls upon encountering the massive infalling outer core for the calculated cores of stars between 8 and 25 solar masses and the standard input physics. In particular, it is found that Nomoto's 8.8 solar mass star and Woosley, Weaver, and Taam's (1980) 10 solar mass star do not explode via the prompt mechanism. The conclusions appear to depend not on the details of the progenitor structures calculated by others but rather on the generic nature of these structures.