Selected mechanisms of matter ejection out of the cometary nuclei

Abstract In the paper we examine two selected mechanisms of matter ejection from the cometary nuclei. The first is a calm sublimation from the comet’s nucleus and the second is the ejection caused by jets produced by cometary geysers. The classical old model which assumes that cometary particles are crumbs of ice-dust solid matter of spherical shapes, as well as modern model of cometary particles treating them as random ballistic aggregates of spherical monomers are considered. Numerical calculations are focused on finding out the maximum sizes of the chunks of matter that can be ejected from comets.