The role of thermal processing in the alteration of complex organic matter

Kurzfassung

Complex organic matter revealed in primitive small bodies shows evidences of early origins from physico-chemical processes taking place in the interstellar medium (ISM) and in the protosolar cloud [1, 2]. In this regard, a relevant contribution to the formation of organic molecules is expected from the exposure of simple H-, C-, N-, and O-bearing ISM ices to low-energy Galactic cosmic rays (GCR) [3, 4]. In the further stages of the Solar System formation, the diffusion and desorption of most volatile species from processed ices, possibly supported by their heating, lead to the production of complex refractory organics [5]. Later on, significant changes are expected to take place in the protoplanetary disk, where thermal processing to high temperatures can determine the formation of amorphous carbon [6] and the loss of astrobiologically-relevant compounds possibly present in pristine organic matter. We simulate in the laboratory the formation of complex organic matter from the exposure of laboratory analogues of ISM ices to energetic charged particles, their subsequent heating to room temperature to form organic refractory residues (ORRs), and their further thermal processing to higher temperatures, with the aim to shed light on the alteration of pristine complex organic matter.