Abstract EANA2025-48

Interstellar icy grains play a crucial role in the formation of complex organic molecules in cold astrophysical environments, such as dense molecular clouds and protoplanetary disks. These grains, composed of silicate or carbonaceous cores coated with volatile ices (e.g., H₂O, CO, CO₂, CH₃OH, NH₃), act as catalytic surfaces where atoms and simple molecules can accrete, migrate, and react under extreme low-temperature conditions (10–20 K).

In this study, we present laboratory simulations of astrochemical processes occurring on icy grain analogs under ultra-high vacuum conditions. Using cryogenic deposition techniques, we prepared thin ice films mimicking interstellar ices and subjected them to UV photolysis and ion irradiation to simulate the energetic processing by cosmic rays and stellar UV fields. The chemical evolution of the ices was monitored in situ via Fourier-transform infrared spectroscopy (FTIR), and post-irradiation products were analyzed through temperature-programmed desorption (TPD) coupled with mass spectrometry.

Our results reveal the formation of a range of complex organic molecules (COMs), including formamide, methylamine, and other prebiotic precursors. These findings support the hypothesis that icy grains function as chemical reactors, enabling the synthesis of biologically relevant molecules even in harsh interstellar conditions. The experimental data also provide reaction pathways and kinetic parameters that can inform astrochemical models and aid in the interpretation of observations from telescopes such as ALMA and JWST.