Multidimensional simulations of mixing in zero- and solar-metallicity SNe

We present multidimensional simulations of zero- and solar- metallicity stars in the last stages of their lives and estimate their resulting nucleosynthetic output. When primordial stars with masses less than about 100 solar masses explode as supernovae, some portion of the star falls back onto the black hole, while the rest escapes to enrich the next generation of stars. The composition of the escaped gas depends on processes that cannot be adequately modeled in one dimension. Multidimensional simulations are needed to capture the inherently asymmetric processes that enrich the outer layers of the star and determine its final yield. We investigate the effects of Rayleigh-Taylor-induced mixing and asymmetries in the explosion on the final composition of the escaped gas. For spherically symmetric explosions, we find that Rayleigh-Taylor-induced mixing has little effect on the shells interior to oxygen, and so very little material interior to the oxygen shell goes on to enrich the interstellar medium. Some asymmetry in the explosion is needed in order for elements interior to oxygen to escape from the star in significant amounts.