Mixing and Nucleosynthesis in Low-Mass Stars

The final phase of the life of a low-mass star is an important time for the formation of many different elements. The unusual structure of these stars opens up many possible pathways for nucleosynthesis as stellar material can be exposed to proton-, neutron- and alpha-captures, via a complex sequence of convective motions. Predictions of state-of-the-art calculations fail to reproduce the abundance patterns observed in many stars (as well as the more precise determinations made in pre-solar grains obtained from meteorites), with some of the lightest elements being a particular problem. This suggests that stellar theory has missed something important: something other than convection is at work in these objects. In this project, the student will compute detailed nucleosynthesis models to determine the characteristics of this missing process. They will investigate how deep material needs to be transport in order to activate the necessary nuclear reactions, and how fast the transport process needs to be. Ultimately, these characteristics will be compared to known non-convective processes with the aim of determining the physical cause of the mixing. 

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