2020ApJ...896...88T

The formation of isomers of C₂H₂O-ketene (H₂CCO), ethynol (HCCOH), and oxirene (c-CHCHO)-was investigated in interstellar ice analogs composed of carbon monoxide and water. Using tunable photoionization time-of-flight mass spectrometry to selectively ionize the isomer of interest, ketene and ethynol were detected as reaction products, but oxirene remains elusive. These findings demonstrate that organic compounds that are precursors to complex organic molecules can form without an organic source of carbon. Furthermore, we report the first plausible detection of ethynol in astrophysically relevant ices. These investigations were supported by theoretical calculations describing reaction energies, pathways, ionization energies, and harmonic frequencies.