ORGANOMETALLIC CATALYSIS FOR AROMATIC-MOLECULES FORMATION IN CARBON-RICH ENVELOPES

Aromatic molecules (PAHs or others) are considered to be an abundant c omponent 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 M edium. We propose that catalytic reactions, based on organometallic ch emistry could contribute efficiently to the formation of such molecule s. A simple model has been developed in the envelope of the well obser ved carbon star IRC+10216. High abundances of small PAHs could be prod uced in the intermediate envelope from the precursor acetylene molecul e. Moreover, the process could be efficient enough to account for the observed depletion of acetylene between the internal and external part s of the envelope (more than one order of magnitude).