Non-gravitational Mechanism of Comets’ Ejection from the Oort Cloud Due to Cometary Outbursts

Abstract

Cometary nuclei located in the Oort cloud accumulate high concentration of radicals in surface layers under cosmic ray irradiation at low temperatures. Recombination of radicals induced by an increase in the surface temperature of a comet by a close passing star, O/B stars, or nearby supernovae leads to the heating of the ice layer with the releasing of volatiles from the amorphous ice. When high gas pressure builds up beneath the cometary surface, dust and gas are ejected. The resulting jet of gas and dust can change the comet’s orbit in the Oort cloud. The studied non-gravitational mechanism can effectively expel comets with a radius of ≤1 km from the Oort cloud into the inner part of the Solar system. The total effect of cometary outbursts on the stability of cometary orbits during the evolution of Solar system can result in a decrease in the number of long-period small-radius comets.