Experimental studies on the evolution of materials from interstellar molecular clouds to proto-planetary disks
For many years, astronomers wanted to know how interstellar molecules, such as H2O, CO, H2CO, CH3OH, NH3, are formed in very cold (around 10 K) molecular clouds. The Arrhenius-type reactions never proceed at around 10 K, and therefore the origin of the interstellar molecules is a mystery. Dr. Kouchi conceived and constructed new experimental set-up to simulate the formation of these molecules under low temperatures and ultra-high vacuum conditions. His experimental studies clarified that the interstellar molecules are formed very efficiently at 10 K by quantum tunneling reactions on the surface of interstellar grains, opening a new field of research in astrochemistry.
Dr. Kouchi’s theoretical and experimental studies were also focused on the formation of amorphous and crystalline ices in molecular clouds and proto-planetary disks. Furthermore, he found that crystalline ices are amorphized by the irradiation of UV-rays. These results have been the standard criterion in describing the crystallinity of ices in space.
Using resonance-enhanced multiphoton ionization spectroscopy, Dr. Kouchi recently confirmed that water formed at 10 K shows a statistical high-temperature ortho-to-para ratio of 3. This finding invalidates the generally accepted relation between the ortho-to-para ratio of water and temperature.
Through these achievements, Dr. Kouchi has provided us a significant understanding of the evolution of materials from interstellar clouds to proto-planetary disks. For these reasons, we are pleased to present the 2020 Miyake Prize to Dr. Akira Kouchi.