Nuclear Reactions Important in Alpha-Rich Freezeouts

Abstract

The alpha-rich freezeout from equilibrium occurs during the core-collapse explosion of a massive star when the supernova shock wave passes through the Si-rich shell of the star. The nuclei are heated to high temperature and broken down into nucleons and alpha particles. These subsequently reassemble as the material expands and cools, thereby producing new heavy nuclei, including a number of important supernova observables. In this paper we introduce two web-based applications. The first displays the results of a reaction-rate sensitivity study of alpha-rich freezeout yields. The second allows the interested reader to run paramaterized explosive silicon burning calculations in which the user inputs his own parameters. These tools are intended to aid in the identification of nuclear reaction rates important for experimental study. We then analyze several iron-group isotopes (59Ni, 57Co, 56Co, and 55Fe) in terms of their roles as observables and examine the reaction rates that are important in their production.