Researchers have shown how gas comes out of ice at an extremely low temperature index. It provides insight into the process of stellar birth in interstellar clouds. Japanese and German scientists have described the mechanism by which hydrogen sulfide is emitted as a gas in interstellar molecular clouds. It is called chemical desorption, and it is more effective than previously thought.
Molecular clouds are rare objects, but are considered important sites where molecules form and evolve. In cooler and denser areas with the right conditions, stars are created. In theory, in molecular regions with a 10 K index, all molecules, except hydrogen and helium, should be in an ice trap on the surface of dust, and not move freely around. However, observations show the opposite.
Understanding how molecules manage to stand out from dust at low temperatures is important for explaining the development of chemicals. The demonstration showed that the dissolution of ice particles due to UV rays (photodesorption) has a certain effect in some parts of the massive clouds. But the effect is reduced in darker and denser areas where stars are born. Scientists have suggested that in these areas chemical desorption works, releasing particles using excess energy from a chemical reaction. The idea was first proposed 50 years ago, but it was not possible to prove it. The situation was decided to correct the representatives of the University of Hokkaido and the University of Stuttgart.
By applying an experimental system containing amorphous solid water at a temperature of 10 K and hydrogen sulfide, the researchers subjected the latter to the influence of hydrogen and monitored the reaction using infrared absorption spectroscopy. It turned out that desorption is caused by the contact of hydrogen and hydrogen sulfide, so the reaction is chemical. They were able to quantify the desorption and show that the effect is more significant than they thought.
The study is important because scientists first carried out IR measurements of chemical desorption and provided detailed descriptions during the reaction. Information provides the keys to understanding interstellar sulfur chemistry.