Nucleosynthesis in rotating pair instability supernovae

The effects of angular momentum on the dynamical collapse and final state of very massive stars are presented. Spherically symmetric stars with He-core masses > 100 M/sub circle/ collapse directly to black holes without producing supernova explosions or ejection of iron peak nuclei. However, the inclusion of a reasonably small amount of angular momentum J at the beginning of the collapse produces enough support so that energy deposition due to explosive oxygen burning halts and reverses the infall, resulting in a very energetic explosion (≥ 1053 erg). Specifically, helium cores of 200, 300, and 500 M/sub circle/ explode for specific angular momentum, JM ≥ 5 x 1017, 2 x 1018, and 4 x 1018 cm2s-1, respectively. Below these values, the cores collapse to black holes. Since lower values of J drive the collapse deeper, higher temperatures are achieved and significant quantities of iron are produced. For example, the smallest J value that yielded an explosion in the 200 M/sub circle/ core produced about 90 M/sub circle/ of iron. Furthermore, the composition profile is asymmetrical while the explosion itself is essentially spherically symmetric. This is a consequence of mixing by vortices established during the time when the collapse was reversed