Formation of carbon grains in the atmosphere of IRC+10216

We investigate the contribution of periodic shocks to the formation of polycyclic aromatic hydrocarbons (PAHs) and their dimers in the inner atmosphere of IRC+10216. The goal of this paper is to look at the implications this has for the formation of carbon dust if PAHs are an intermediate step. It is shown that the amount of PAHs and dimers produced is not enough to explain the formation of carbon dust in the atmosphere of the star, but it can account for the formation of the small disordered cores of the kind observed in presolar grains.