Cosmic dust as laboratories for chemical processes: results from the first quarter of the project
The project "Multi-material dust astrochemistry (DACE)" (lzp-2025/1-0065) established a research team in the first quarter and began work to better understand the processes that determine molecule formation in the interstellar medium. The project involves leading researchers J. Kalvāns and J. Freimanis, doctoral student K. Veitners, as well as bachelor's students in chemistry from the University of Latvia, N. Muhaņko and D. Brakšs. On February 18, the project's opening seminar took place.
In the first research direction of the project, the properties of interstellar dust are being studied. Although these dust particles are very small, they play a crucial role in the chemistry of the Universe. New molecules form on the surfaces of the dust, and their temperature influences the course of these processes. Therefore, models are being developed to calculate the temperature of dust in various cosmic environments.
The temperature of dust is determined by the balance between heating and cooling. It is heated by various radiation sources – nearby stars, interstellar ultraviolet radiation, photons generated by cosmic rays, and cosmic microwave background radiation. Cooling, on the other hand, occurs as the dust emits heat and transfers energy to the surrounding gas. Since different dust materials absorb and emit radiation in different ways, the project is compiling data on their physical properties and interactions with the surrounding environment.
The second research direction focuses on improving astrochemical models that describe chemical reactions in space. The internationally used reaction database, UDfA Rate22, has been selected as the foundation for this work and will be expanded to include reactions that occur on dust-grain surfaces.
Unlike reactions occurring in the gas phase, dust grain surfaces act as natural micro-laboratories. They allow molecules to remain in close proximity for longer periods, thereby facilitating chemical reactions. In addition, the surface can absorb excess energy released during reactions, helping to stabilize newly formed molecules. As a result, many reactions proceed more efficiently on dust grain surfaces than in the free gas.
At present, particular attention is being devoted to reactions involving compounds of magnesium, calcium, titanium, iron, and sulfur, which have received little attention in astrochemical surface-reaction databases to date. At the same time, the potential use of another recently developed astrochemical reaction database, KIDA 2024, is being evaluated for specialized studies.
The overall goal of the project is to develop a comprehensive picture of the distribution and composition of ice on dust grains composed of different materials in the interstellar medium and in star-forming regions. To achieve this, the project will develop the necessary methodology and investigate several key aspects of multi-material dust–ice chemistry through numerical simulations. The results will contribute to a better understanding of radioastronomical observations of ice-related molecules, the chemical transformations taking place within interstellar ices, and the transport of ice in the inner regions of star-forming nebulae.
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