Summary:
Interstellar and circumstellar ices are largely composed of frozen H2O.
Therefore, it is important to derive fundamental parameters for H2O ice such as absorption and scattering opacities, for which accurate complex refractive indexes are needed. With this motivation, we derived temperature-dependent mid-IR H2O ice refractive indexes based on recent laboratory experiments, and we explored the astrophysical implications of these new values compared to previous data available in the literature. For this, we made use of different computational codes, including optool to derive icy grain opacities and RADMC-3D for simulating a protostellar envelope with icy grains. We highlight two results from this research. First, the direct impact on the ice column densities derived from the simulations of embedded protostars when the new refractive indexes of H2O ice are used. The second result is related to the size of icy grains where the H2O IR ice bands remain detectable by telescopes. Our research found a size threshold of 18 µm micron for the O-H mode at 3 µm.

Article link:  https://www.aanda.org/articles/aa/full_html/2024/01/aa47437-23/aa47437-23.html