Influence of hydrothermal asteroidal conditions on the molecular structure and isotopic compositions of polycyclic aromatic hydrocarbons

A variety of polycyclic aromatic hydrocarbons (PAHs) are reported in carbonaceous chondrites (CCs) and the interstellar medium (ISM). Although PAHs CCs not as large those detected ISM, their carbon isotope composition is interpreted pinpointing an origin. In contrast, hydrogen can be related to extent secondary processes, proportion alkylated within CCs. Here, we experimentally investigate molecular isotopic evolution under simulated asteroidal hydrothermal conditions at 150 °C. Results show that chemically stable these whatever size, i.e. no destruction, conjugation nor alkylation occurs, even presence other reactive organic molecules. Plus, retain compositions another carbon-rich reservoir, either or inorganic. On hand, modified through exchange with water. Of note, shown by additional experiments, smectites, abundant CCs, impacts relative abundances extractable PAHs, saponite trapping more efficiently larger PAHs. Altogether, results present experiments used tracers both pre-accretion processes.