Physical properties of methanol (CH3OH) ice as a function of temperature: density, infrared band strengths, and crystallization

ABSTRACT The presence of methanol among the common ice components in interstellar clouds and protostellar envelopes has been confirmed by the James Webb Space Telescope (McClure et al. 2023). Methanol is often detected in the gas phase towards lines of sight shielded from UV radiation. We measured the volumetric density of methanol ice grown under simulated interstellar conditions and the infrared spectroscopy at different deposition temperatures and during the warm-up. The IR band strengths are provided, and the experimental spectra are compared to those computed with a model. The transition from amorphous to crystalline methanol ice was also explored. Finally, we propose new observations of methanol ice at high resolution to probe the methanol ice structure.