Organometallic catalysis for aromatic molecules formation in carbon rich envelopes

Aromaticmolecules (PAHs or others) are considered to be an abundant component of the Interstellar Matter. However, their formation process remains a problem since a high production rate is required in order to balance the destruction mainly caused by shocks in the Interstellar Medium. We propose that catalytic reactions, based on organometallic chemistry could contribute efficiently to the formation of such molecules. A simple model has been developed in the envelope of the well observed carbon star IRC+10216. High abundances of small PAHs could be produced in the intermediate envelope from the precursor acetylene molecule. Moreover, the process could be efficient enough to account for the observed depletion of acetylene between the internal and external parts of the envelope (more than one order of magnitude).