Belousov D.V.

Ioffe Physical-Technical Institute of the RAS, St. Petersburg

Simulation of energy accumulation in icy bodies during irradiation: a source

of cometary activity far from the Sun.

Abstract

Many icy bodies in the solar system (e.g., comets and Kuiper Belt objects)

demonstrate activity far from the Sun. The nature of such an activity remains one

of the main enigmas of planetology. Comet nuclei undergo a constant

bombardment by galactic cosmic rays (GCR) and solar cosmic rays (SCR) during

their storage in the Oort Cloud and the Kuiper Belt. Long-term cosmic ray

irradiation produces chemical and physical changes in comet ice with the

formation of radicals. It is well-known that trapped radicals at low temperatures are

prone to fast recombination with marked energy release; recombination can be

induced by external heating or occurs spontaneously reaching the critical

concentration of radicals. A similar process could take place in the radicals-

enriched subsurface layer during the sunward voyage of a dynamically “new”

comet. Also, located in the Oort Cloud cometary nuclei can experience activity

driven by spontaneous recombination.