Production of hexamethylenetetramine in photolyzed and irradiated interstellar cometary ice analogs

We report hexamethylenetetramine (HMT) detection in organic residues resulting from H2O : CO : CH3OH : NH3 ices submitted to UV photolysis or proton irradiation. This is the first time HMT is detected after proton irradiation of an interstellar or cometary ice analog, whereas this molecule was suspected to be a characteristic signature of UV versus ion processing. This result strengthens the probability of HMT presence in the interstellar medium and in comets, where it may eventually be detected with the COSAC (COmetary Sampling And Composition) experiment on board the upcoming Rosetta mission.