The Cold and Hot CNO Cycles

New experimental methods and techniques, combined with the development of new theoretical tools, have opened new avenues to explore nuclear reactions of significance for nucleosynthesis at or near the actual temperatures of stellar burning. In particular, many reactions of the cold and hot CNO cycles have been investigated in recent years to provide a complete understanding of this critical hydrogen-burning mechanism in stars and stellar explosions. This has led to new interpretations of or new signatures for a number of critical hydrogen-burning environments and events. This article provides a summary of the most recent discoveries and results associated with CNO reactions, and it identifies existing shortcomings in the data as well as needs and opportunities for additional future experiments.