Abstract
We have simulated the collapse and evolution of the core of a solar-metallicity 40 M-circle dot star and find that it explodes vigorously by the neutrino mechanism, despite its very high "compactness." Within similar to 1.5 s of explosion, a black hole forms. The explosion is very asymmetrical and has a total explosion energy of similar to 1.6 x 10(51) erg. At black hole formation, its baryon mass is similar to 2.434 M-circle dot and gravitational mass is 2.286 M-circle dot. Seven seconds after black hole formation, an additional similar to 0.2 M-circle dot is accreted, leaving a black hole baryon mass of similar to 2.63 M-circle dot. A disk forms around the proto-neutron star, from which a pair of neutrino-driven jets emanates. These jets accelerate some of the matter up to speeds of similar to 45,000 km s(-1) and contain matter with entropies of similar to 50. The large spatial asymmetry in the explosion results in a residual black hole recoil speed of similar to 1000 km s(-1). This novel black hole formation channel now joins the other black hole formation channel between similar to 12 and similar to 15 M-circle dot discovered previously and implies that the black hole/neutron star birth ratio for solar-metallicity stars could be similar to 20%. However, one channel leaves black holes in perhaps the similar to 5-15 M-circle dot range with low kick speeds, while the other leaves black holes in perhaps the similar to 2.5-3.0 M-circle dot mass range with high kick speeds. However, even similar to 8.8 s after core bounce the newly formed black hole is still accreting at a rate of similar to 2 x 10(-2)M(circle dot) s(-1), and whether the black hole eventually achieves a significantly larger mass over time is yet to be determined.