Synthesis of Nuclei with

Eventually, the helium of the star will be exhausted, leading to further gravitational collapse with a temperature increase to 6 x 108-2 x 109 K (kT 100-200 keV). At this point the fusion reactions of the a-cluster nuclei are possible. For example, 

The nuclei up to A 60 are produced in these equilibrium processes. In such equilibrium processes, the final yields of various nuclei are directly related to their nuclear stability with the more stable nuclei having higher yields. So one observes greater yields of even-even nuclei than odd A nuclei (due to the pairing term in the mass formula) and even N isotopes are more abundant than odd A isotopes of an element. 

The relative time scales of the various reactions leading to nuclei with A 60 are shown in Table 12.2. Note these time scales are inversely proportional to the reaction rates. 

TABLE 12.2 Time Scales of Nucleosynthetic Reactions in a 1 Solar Mass Star 

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