PAHs, Carbon Clusters and Fullerenes in Cosmic Dust Analogues and Meteorites

Abstract

Large carbonaceous molecules such as polycyclic aromatic hydrocarbons (PAHs) and fullerenes are abundant species in astrophysical environments but only a few specific molecules, mainly C$_{60}$ and some two-ring aromatics, have been identified so far. Targeting specific species of these families raises the question of their formation, particularly in the hot and dense envelopes of evolved stars. This has motivated a number of research groups to produce cosmic dust analogues using a variety of techniques. Laboratory analysis of extraterrestrial matter such as meteorites can also provide additional clues regarding the origin of these molecules and their physical and chemical evolution. In this work, we present a new experimental setup, the Astrochemistry Research of Organics with Molecular Analyzer (AROMA) and demonstrate its potential to probe PAHs, carbon clusters, and fullerenes in cosmic dust analogues and meteorite samples. We have analyzed Murchison and Allende, the two most studied carbonaceous chondrites, as well as the Almahata Sitta ureilite. The same technique is used to analyze cosmic dust analogues such as those produced by the Stardust machine. Hundreds of peaks are identified in the mass spectra with notable discrepancies between the different types of samples. Here we present our ability to use these discrepancies to better understand the chemical history of each sample. Ultimately, our approach can help elucidate the role of these species in the formation and evolution of carbonaceous cosmic grains.