How radiation affects interstellar and solar system ice mantles

Abstract

In space, ices containing simple molecules such as H2O, CO, CO2, and NH3 are omnipresent. More complex molecules have also been observed. In our solar system, ices exist for example in comets, on the moons of the giant planets, and on trans-Neptunian objects. In outer space, these molecules can form icy mantles on dust grains in dense molecular clouds - the birthplaces of stars and planetary systems - at temperatures as low as 10 K. They are exposed to the complex radiation field in space consisting of photons (UV, x-rays), electrons and ions (stellar winds, particles trapped in magnetospheres, galactic cosmic rays). This in turn induces physico-chemical modifications. Physical processes include compaction, amorphization and desorption Chemical modifications occur since fragmentation of the molecules leads to formation of radicals (radiolysis), and subsequent synthesis of new molecular species. Even complex pre-biotic molecules such as amino acids can be synthesized, and an extraterrestrial origin of such molecules and therefore of the emergence of life on earth or elsewhere is conceivable. Implantation of heavy reactive ions (C, N, S) can contribute to the formation of molecules. Laboratory experiments can simulate the radiation processing of ices occurring in space and help to understand astronomical observations.

Pre-colloquium for students at 15:30
with title: "How to simulate cosmic rays and solar wind interaction with astrophysical materials in the laboratory"